An energy company has apologised after it told a customer he was £950 in credit when giving his final bill - only to go back to him months later and tell him he OWED £1,500.

When dad-of-two Andrew Shaw moved out of his house in Chesterfield, Derbyshire, last July, he took final meter readings and was told by First Utility he was £950.54 in credit.

But five months later, it said there had been a mistake and he owed £1,562.41 - including the £950.54 credit which had been previously sent to him. 

Andrew had already spent the money on home improvements on his new house, but despite admitting its service was "below-standard" and offering a goodwill gesture, First Utility has not offered to cancel the bill.

See our Cheap Gas and Electricity guide for more information.

'We're left in £1,500 of debt through no fault of our own'

Andrew, 34, says when he was initially offered the refund by First Utility after sending images of his meter readings, he asked the team to double-check and confirm he was owed £950.

He switched provider when he moved house, but First Utility contacted him around Christmas time last year saying he owed money.

Andrew said: "When I was initially told I was in credit [First Utility] double-checked this and ran it past a manager, they confirmed the amount was correct and that I needed to send them photographs of the meters for them to check and then release the money.  Photographs were sent and the money was then sent, I believe via a cheque.

"We have spent the money on house renovations believing that it was ours to spend as we wished, there was never any indication that we may have to pay it back.

"We're left in £1,500 of debt through no fault of our own. We're now in financial difficulty. Obviously I wouldn't have spent the money if I hadn't had it."

Andrew is now considering whether to escalate his case. For more information on how to complain about your energy provider, see our Cheap Gas and Electricity guide.

First Utility: 'We apologise for the inconvenience we caused'

After we contacted First Utility to ask about the situation, it offered Andrew a "goodwill gesture", but remains adamant he must repay the bill.

It said:"We are sorry for the below-standard service that  Mr Shaw has experienced in regard to his final bill. When Mr Shaw moved out of his previous property in July 2017, we issued him with a final bill that was incorrectly calculated and showed that he was in credit by £950.54, rather than showing the correct balance of £611.87 debt.

"As soon as the mistake was identified in December 2017, we contacted Mr Shaw to explain our shortcomings and sent him an accurate bill showing that he is in debt by £1,562.41 - including the £950.54 credit which had been previously sent to him. 

"We have since apologised to Mr Shaw, offered him a payment plan and have also agreed to issue him a goodwill gesture for our mistake."

What are the rules on this?

Unfortunately, the regulator Ofgem doesn't have clear guidelines on this.

Its licence conditions - which energy firms sign up to - state companies must take all reasonable steps to send a final bill within six weeks of the end of a contract.

They also say if an error is made, a company must send a corrected bill or statement as soon as is "reasonably practicable after the subsequent information becomes available."

From April, however, all energy firms will be banned from back-billing customers beyond 12 months under stricter new rules.

Six firms, including British Gas, E.on and EDF, already agree not to bill customers beyond 12 months as part of a voluntary scheme, but Ofgem says even these companies don't always follow these rules and so it's putting in place a ban that will apply to the whole sector.