Energy suppliers are still taking unnecessarily high direct debit payments from millions of customers each month.

A survey by Which? the consumer group, found that 65 per cent of respondents are in credit with their energy supplier but are still being overcharged. A quarter were owed at least £100 – despite the research taking place in winter, when energy use is normally higher.

Around 12 million households pay for their energy with direct debit, according to Ofgem, suggesting as many as 7.8 million people could be paying too much. Which? says that suppliers are using their customers’ money as “interest-free loans.”

Martyn Hocking of Which? Money said: “It seems incredible that energy companies can take hundreds of pounds more than they need to from their customers, and profit from the interest that this money will earn at our expense.

“While a small amount of credit built up over the summer months can be used up during the winter, it’s difficult to see how a £200 credit will be used up – particularly as the customer makes the same payment each month.”

Energy companies encourage consumers to pay by monthly direct debit by making it cheaper than paying quarterly. However, because the monthly amounts are estimates of how much gas or electricity a customer is using, they can often be wrong.

Which? found that the average amount in credit was £74 for electricity and £84 for gas, although 8 per cent of respondents were owed more than £200.

Ofgem, the energy regulator, is currently investigating direct debit demands and will publish its findings later this month. It comes after Peter Luff, the Conservative MP, handed Ofgem a dossier of evidence in December from his constituents in Mid-Worcestershire detailing households that have suffered significant increases to their direct debits.

Which?’s survey also found that energy suppliers are one of the worst industries at delivering customer satisfaction. Npower was deemed the worst energy provider, with a satisfaction score of only 30 per cent. Utility Warehouse achieved the highest customer satisfaction score of 83 per cent.

Mr. Hocking added: “Consumers are advised to regularly check their meter readings and the direct debit amount, and to contact their supplier if what they are paying does not accurately represent their usage. “

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