The energy watchdog imposed a limit of £88 on how much more pre-pay customers could be charged than those paying by direct debit following a major investigation in September into whether pre-pay customers were being penalised.  But, according to the NHF, Centrica-owned British Gas, Scottish Power – which is owned by Spain's Iberdrola – German company E.ON, Scottish & Southern Energy and npower, owned by Germany's RWE, are all failing to meet the cap.  The companies have 6m pre-payment meter customers between them.  The NHF, which represents 1,200 housing associations in England, said the charges, said to cover the extra expense of installing a meter, vary across suppliers. For example, E.ON, charged pre-pay customers £99 more than those on direct debits, while Scottish Power customers paid £108 more.  EDF was the only one of the major companies that did not overcharge, the federation said.  The meters are usually used by people on low incomes or customers who have a second home which they visit infrequently.  David Orr, chief executive at NHF, has written to Ofgem demanding an investigation into whether firms have breached their licence conditions.  He said: "The fact that five of the big six energy companies have already ignored the new licensing conditions shows that Ofgem simply isn't taken seriously by the energy industry.  "Ofgem will now have lost the confidence of millions of pre-pay customers across the country."  An Ofgem spokesman said: "The licence conditions ensure that the differences between payment methods are cost-reflective and there are no unjustified price differences.  "As part of our retail market probe investigation in 2008, we estimated the cost difference between pre-pay meters and direct debit.  "However, it was never our intention to stipulate a maximum acceptable cost difference, as we accept that suppliers' costs for providing payment methods change."  The Energy Retail Association, the industry trade body, denied its members were infringing their licence conditions.
Five of the "big six" energy suppliers still overcharge customers on    pre-pay meters despite new Ofgem rules, according to the National Housing    Federation (NHF).