Research by Moneysupermarket shows that pre-payment energy customers could be losing out on as much as £769m worth of savings.

This is because the average pre-payment tariff is £150 more expensive for gas and electricity than the best value rate.

A spokesperson for Moneysupermarket said: “Pre-payment customers should not be punished for using this type of meter. It is painfully ironic that they pay a hefty price and are charged 17% more on average than those who pay by monthly Direct Debit.

“In the Budget this year the Government put forward proposals to treat pre-payment customers fairly. It is high time these promises are put into action. Energy providers should look to reduce prices for pre-payment customers, remove back charges completely and pledge to shield them from further anticipated price hikes this year.

“Following the price hikes this year, an estimated half a million more households have plunged into fuel poverty and without action from energy providers and the Government, it is likely that more could slip into this situation. For vulnerable customers who are struggling to pay for their energy bills I advise them to speak to their supplier who may be able to offer special social tariffs or give information on swapping to a credit meter, or advice on other discounts.”