Prepay meters are still being used to overcharge customers by all but one of the major power companies, despite new Ofgem guidelines requiring the firms to switch energy practices, according to the National Housing Federation (NHF).
Ofgem recently introduced new rules stating that consumer prices must reflect the costs incurred by energy suppliers when processing different payment methods, but the NHF claims prepay customers are being charged more than the extra £88 a year their billing system costs to process.
The NHF claims that EDF is the only major supplier not currently overcharging prepay customers and the NHF is seeking a formal investigation to check whether licences are being breached.
David Orr, chief executive of the NHF, said: "Ofgem will now have lost the confidence of millions of prepay customers across the country. The situation is an absolute disgrace."
The Energy Retail Association, which represents the UK's energy suppliers, said licence conditions were not being infringed.
Prepay customers tend to more vulnerable than those paying by direct debit and they often more at risk of falling into fuel poverty.
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