British Gas will avoid potentially costly enforcement by the energy regulator after agreeing to pay £1.73 million for not telling some customers they would need to top up their meter cards at a different shop until almost a month after the switch.

Ofgem said Britain’s biggest energy supplier would have left many vulnerable customers in a difficult situation when it failed to tell them in time that it was switching meter top-ups from PayPoint to Payzone earlier this year.

Some people may have been left without energy, and others would have made unnecessary trips to shops where they were no longer able to top up.

Adding to the confusion, the British Gas helpline was not being manned on New Year’s Day when the switchover happened.

The company has agreed to pay £1.48 million to affected customers, and will pay an extra £250,000 into Ofgem’s energy redress fund.

“When such a fundamental change is being made, such as where meters can be topped up, energy suppliers need to communicate with their customers in plenty of time,” said Ofgem director of retail Philippa Pickford.

“British Gas should have informed all of their pre-payment customers, many of whom are in vulnerable situations, of the change to how to top up their meters during the winter period.”

Around 270,000 pre-payment customers were not properly informed of the switch, with some letters coming in late January, according to the regulator.

British Gas told most of its customers of the change in December 2019, which did not leave enough time for unhappy customers to switch to a new supplier.

The letters also did not tell customers that the minimum top-up had been changed from £1 to £5, Ofgem said.

“Some customers were unaware of the change before it happened and may have struggled to contact British Gas as they opted not to open their general inquiries line on the go-live date,” Ms Pickford said.

“Others were given insufficient time to make alternative arrangements if they were unhappy with the change of top-up provider.”

British Gas said: “We recognise that this transition was not as smooth as it should have been and we would like to apologise again to any customer impacted.

“We respect Ofgem’s decision and will be paying an additional £250,000 to the voluntary redress fund. We have already paid £1.48 million in compensation to our pre-payment customers who were negatively impacted by this change.

“We know that some pre-payment customers are vulnerable and we take our responsibilities to them very seriously.

“We ensured that anyone who contacted us had heating and hot water – this included sending an engineer to manually add credit to the meter if the customer was unable to get to their nearest working top-up point.”

Ofgem said some of the letters to customers did not have a phone number, merely providing internet links, which could disadvantage people with little understanding of, or no access to, the internet.

Citizens Advice boss Dame Gillian Guy said: “It is unacceptable that poor communications put people at risk of being cut off from their energy supply in the middle of winter.

“Households with pre-payment meters are disproportionately likely to be on lower incomes, have children or include people with health conditions. So it’s critical that suppliers take extra care and make sure changes like this don’t put people at risk.”