Alison Woods lives frugally by herself in a two-bedroom flat, but as far as British Gas is concerned she is burning through enough energy to fuel a cannabis farm. The estimated readings on the quarterly bill that arrived in March were up by 1,000% on the same period last year. At nearly £2,000, the cost was more than the average household pays in a year, according to Ofgem estimates. Woods has a smart meter and usually pays between £70 and £110 a month.
“I have not changed my habits in any way,” she said. She has tried several times to complain to the company. “Every time I open a complaint, I receive a response that firstly ignores any of my questions about how my bill could be so high, secondly uses the same stock phrases and makes me think it is written by a bot, and thirdly tells me the complaint has now been resolved as everything is in order,” she said. “It is causing me so much stress and lost sleep.”
After Guardian Money intervened British Gas discovered that it had botched the transfer of Woods’s account to its new billing platform. Her gas meter reading had been wrongly recorded on the new system and she had been billed for months’ worth of energy that she had already paid for.
It seems that she is not alone.
In 2021, Centrica, British Gas’s parent company, announced that it would be moving more than 7 million customers to a new system to enable them to manage their accounts digitally.
British Gas, whose profits increased more than tenfold last year to £751m, told customers that the aim was make its operations simpler and more efficient and promised to pass on resulting cost savings. However, for some the switch has unleashed chaos: they have reported shock bills and missing credits after being given new accounts.
Chris Timpson* and his wife were told they owed £1,919 for a month’s worth of energy in January. The bill was amended to £77 when they complained, but in April they were charged £1,259.
“We live in a small retirement flat and for the last three years have used two Dyson heaters rather than our gas central heating to save money,” he said. “Last December, British Gas updated its system and the new app showed energy statements for the last 12 months which were up to 1,100% higher than the amounts we’d actually paid.”
British Gas discovered that it had entered an erroneous meter reading on the new system after we got involved. The Timpsons actually owed £195, which it wrote off as a gesture of goodwill.
Fiona Porter’s balance went haywire after her account was transferred in December 2022. “Statements under the old account number showed I was £1,525 in credit and this was confirmed twice over the phone over the next seven months,” she said. “We had moved out of our house in April 2023 and were promised the refund when it was sold that September, but instead we received a final bill for £1,594.”
Porter complained to the ombudsman who ordered British Gas to recalculate her bill. In March this year, the company informed her that she was, in fact, £2,650 in credit and promised a cheque within 14 days. It never came. Ten days later she received a demand for £1,449 and has since been told that she owes £3,000 and faces debt collectors.
A letter from customer services explained that the confusion arose when her account was transferred to the new system and that the credit in her statements was actually a debt.
British Gas told us that billing errors on Porter’s account stemmed from a faulty meter that was replaced in 2021 and insisted that her experience was unrelated to the new platform. It admitted that Porter was informed that her account was in credit before it was migrated but says this was human error. After contact from Guardian Money, it credited her account with an unexplained £1,201. She insists she is still owed the £2,650 credit.
A spokesperson said: “Ms Porter’s complaint has already been reviewed by the energy ombudsman and we applied the remedies requested of us in terms of recalculating her bill. Ms Porter is still querying the bill and we are currently in touch with her as we do want to get this resolved.”
In 2017 British Gas was ordered to pay £9.5m in compensation by the energy regulator, Ofgem, after a new billing system left business customers with inaccurate bills. Ofgem said that it was monitoring complaints about the latest IT upgrade.
“We are aware of this issue and have contacted British Gas to ask for more information about the scale of the issue and find out what they are doing to address the situation and protect their customers,” said a spokesperson. “We expect all suppliers to bill their customers accurately and when errors are identified they should be rectified as quickly as possible. To not do this is unacceptable.”
British Gas declined to comment on the record on the other cases.
* Names changed
• This article was amended on 8 June 2024 to remove an incorrect reference to British Gas using Octopus Energy’s Kraken technology platform.
