Diamond Green Energy Ltd: most-reported complaints
Automated analysis of 242 public Trustpilot reviews published 2017-07-29 to 2026-09-01. TrustScore 4.9 from 2,712 total reviews — see the Trustpilot page. Quick answer: is Diamond Green Energy Ltd legit? Issues below reflect what reviewers reported, not findings of wrongdoing.
Reviewers most often report that support staff are unhelpful, accounting for 30% of the 23 complaints identified. Missed appointments and poor core service are also frequent issues, each cited in 22% of complaints. Additionally, 13% of complaints mention late delivery of services. No specific trend can be established for these issues due to a lack of sufficient review data.
How to reach Diamond Green Energy Ltd
These are the contact details Diamond Green Energy Ltd publishes on its Trustpilot profile, as of our last check on 2026-09-24 — phone 01329 234111, address Unit 4, Apex Centre, Speedfields Park, Fareham, PO14 1TP, GB.
The company claimed its Trustpilot profile on 2017-06-07, uses Trustpilot’s paid features, and last replied to a negative review on 2026-05-18. Trustpilot ranks it 10 of 47 in Gas Installation Service. We last checked this profile on 2026-09-24 and found 5 new reviews. These are facts Trustpilot publishes about the profile, as of our last harvest.
Forum footprint: 0 MoneySavingExpert forum discussions mention this company (browse). Roughly 0 of the top, relevance-sorted search results were posted in the last 90 days — an approximate figure by construction, not a true recency count.
Elsewhere: 4.7★ on Google (0 reviews)
TrustScore over time
4.9 → 4.9 across 13 census measurements since 2026-08-12. Our own record, independent of Trustpilot’s display.
Reply behaviour over time
Solid: % of negative reviews replied to. Dashed: typical days to reply. Both as reported on this company’s Trustpilot profile, recorded whenever our census re-checked it and a figure had changed — the gaps between points are not equal: 2026-08-12 (100%, 9.7d) · 2026-08-15 (100%, 9.7d) · 2026-08-18 (100%, 9.7d) · 2026-08-21 (100%, 9.7d) · 2026-08-24 (100%, 9.7d) · 2026-08-27 (100%, 9.7d) · 2026-08-30 (100%, 9.7d) · 2026-09-02 (100%, 9.7d) · 2026-09-08 (100%, 9.7d) · 2026-09-12 (100%, 9.7d) · 2026-09-15 (100%, 9.7d) · 2026-09-18 (100%, 9.7d) · 2026-09-24 (100%, 9.7d).
Severity: 9% of this company’s 23 graded complaints were classified as severe (money lost, an essential service cut off, or a problem unresolved for months). See the harm index.
What their policy promises
complaint process: promptly and effectively
“We will deal with your complaint promptly and effectively in a positive manner.”
complaint process: 5 working days
“We will acknowledge receipt of your complaint within 5 working days”
complaint process: 14 days
“initially contact you either by telephone or email to discuss your complaint and agree to a plan to resolve the issue within 14 days if not sooner.”
complaint process: 8 weeks
“If we are unable to provide you with a final response within 14 days we may extend this to a timeframe of 8 weeks”
Quoted verbatim from the company’s own published policy (source page); complaint counts are census classifications. As of 2026-09-12.
Policy-page monitoring
We monitor this company’s published policy page for changes. No changes have been detected since we started watching on 2026-09-01.
Automated change detection on the company’s own published policy page — a record of when the page changed, not a judgement on what changed.
Reply quality: of 22 company replies to negative reviews analysed, 18% engaged with the specific problem and 9% were generic templates.
Review provenance: 210 company-invited reviews in the recent window average 4.92★, while 20 organic (uninvited) reviews average 4.85★.
6% of its 218 recent 5★ reviews came from accounts that had written only that one review when we captured it (the median across companies is about 39%). A high share is a reason to look closer, not evidence of fake reviews.
Sector benchmark: support unhelpful makes up 30% of this company’s complaints vs a 29% median across 111 ranked companies in its sector.
Review velocity: 311 of this company’s 2,712 Trustpilot reviews (11%) were written in the last 12 months.
Not enough reviews to establish a trend.
What are the most common complaints about Diamond Green Energy Ltd?
Support unhelpful
7 reports · 30% of complaints“His manner was gruff at best and I was not happy to have him in my home”
The company replied on 2022-01-21: “I am really sorry that you feel this way. Having spoken with both you and our engineer I really do think this is an unfortunate review. The engineer you are referring to regularly receives exemplary…”
Our classifier read this reply as a deflection.
2 readers marked this review helpful on Trustpilot.
“Found heat exchanger was leaking and advised replacement. Around £600 in total”
The company replied on 2021-01-21: “Dear Mr Jamie. R . You contacted us to service your boiler which had not been serviced for 7 years. We diagnosed a leak on a heat exchanger and gave you a possible cost if you needed to replace it.…”
Our classifier read this reply as a deflection.
1 reader marked this review helpful on Trustpilot.
“we had to chase up the company the day before to find out when the engineer was coming”
The company replied on 2025-09-10: “Dear VB, Our system is automated and when the route is optimised all our customers will receive a text - these texts will be sent out the evening before the appointment informing you of a time. I can…”
Our classifier read this reply as a deflection.
1 reader marked this review helpful on Trustpilot.
Missed appointments
5 reports · 22% of complaints“No contact from technician by 13.00 so called and was told he was held up”
1 reader marked this review helpful on Trustpilot.
“By 2.30pm I had to phone the office as he still hadn’t arrived.”
The company replied on 2021-11-22: “Dear Mrs Andrews thank you for your review, it is really important to us. This time of year is extremely busy for a gas and heating company as you can imagine, it is for this reason that timings are…”
Our classifier read this reply as a substantive response.
It promised: refund.
1 reader marked this review helpful on Trustpilot.
“the engineer turned up at the wrong time and as I wasn’t there my service couldn’t be done.”
The company replied on 2017-10-30: “Dear Mrs Adams, Thank you for taking the time to review. We apologise that we could not service your boiler due to nobody being at home. Our notes show that you requested that we avoid certain times…”
Our classifier read this reply as a deflection.
1 reader marked this review helpful on Trustpilot.
Poor core service
5 reports · 22% of complaints“The emergency technician stood on the kitchen worktop in his shoes ! No overshoes or surface covering ... just straight onto the worktops”
The company replied on 2021-03-21: “Dear Mr Arkell, I am equally disappointed that you felt you could not call to talk things through before writing such a damning review. Especially as you called Saturday morning, we sent an engineer…”
Our classifier read this reply as a deflection.
2 readers marked this review helpful on Trustpilot.
“Unfortunately I had no hot water after the engineer visited”
The company replied on 2023-06-08: “Having spoken with our engineer, your boiler was fully pressurised and working when he left and the pressure was left at 1.1 bar. No leaks were detected on the servicing of your boiler either. We…”
Our classifier read this reply as a deflection.
1 reader marked this review helpful on Trustpilot.
“No contact from technician by 13.00 so called and was told he was held up”
1 reader marked this review helpful on Trustpilot.
Delivery late
3 reports · 13% of complaints“Arrival expected between 11 and 3pm and arrived at 4:45pm”
The company replied on 2026-02-05: “Thank you for taking the time to provide your feedback. As explained to you over the phone when you contacted us, the engineer was unfortunately running behind schedule. While we always aim to meet…”
Our classifier read this reply as a deflection.
1 reader marked this review helpful on Trustpilot.
“By 2.30pm I had to phone the office as he still hadn’t arrived.”
The company replied on 2021-11-22: “Dear Mrs Andrews thank you for your review, it is really important to us. This time of year is extremely busy for a gas and heating company as you can imagine, it is for this reason that timings are…”
Our classifier read this reply as a substantive response.
It promised: refund.
1 reader marked this review helpful on Trustpilot.
“you were meant to come am, i had set up a legal appointment in the afternoon as you were due am, he arrived around 2pm”
The company replied on 2021-06-03: “Thank you for your review Mr Miskella, It is really important to us and we will always strive to improve our services where we can. The nature of the business sometimes means certain jobs run over…”
Our classifier read this reply as a deflection.
1 reader marked this review helpful on Trustpilot.
Other
2 reports · 9% of complaints“engineers should wear overshoes when entering areas with carpets. That was our only gripe.”
The company replied on 2021-12-09: “All our engineers carry shoe coverings and facemasks on the vans and I sincerely apologise that company policy has not been adhered to on this occasion. I will be highlighting your review to all…”
Our classifier read this reply as a substantive response.
1 reader marked this review helpful on Trustpilot.
“let down by some of their fitters”
1 reader marked this review helpful on Trustpilot.
Support unreachable
2 reports · 9% of complaints“so far I received no response and reply”
The company replied on 2020-03-16: “Dear Ms Yan, I believe that your queries have now been rectified, following your conversation with Ian.”
Our classifier read this reply as a substantive response.
1 reader marked this review helpful on Trustpilot.
“asked for paper work to be sent ie guarantee not replied to.”
The company replied on 2017-07-29: “Dear Mrs Winning, thank you for taking the time to review. Your Existing gas pipe work was not sufficient for your new boiler which was only established when commissioning. We then upgraded the pipe…”
Our classifier read this reply as a deflection.
Compare Diamond Green Energy Ltd with…
Method: reviews are classified into a fixed complaint taxonomy by an automated reader; every category shown is backed by at least two verbatim quotes from distinct reviews. Trends are computed from dated review counts only. Negative reviews are deliberately over-sampled for evidence depth; headline percentages use an unbiased recent sample only. Report updated 2026-09-07.