The UK’s six largest energy companies have agreed to hand back hundreds of millions of pounds to customers from closed accounts.
The cash is part of a “build up” suppliers today promised to keep on top of.
Regulator Ofgem said it uncovered the practice of keeping money from customers who left for other suppliers and welcomed the “new efforts” from suppliers.
More than £153m are expected to be refunded to 3.5 million domestic customers after the cash accumulated in closed accounts in the past six years.
Householders who think they could be owed money are advised to contact their previous supplier.
Dermot Nolan, Ofgem Chief Executive said: “This issue is part of a wider challenge of delivering good customer service that the industry must crack if they are to rebuild customer trust and confidence.”
He added: “And while Ofgem welcomes the progress made to date, suppliers must now do everything within their powers to return the money and prevent a similar situation from happening again. Failure to deliver on the initiatives announced today could trigger further action by Ofgem, including enforcement.”