The number of energy tariffs available to householders is so vast and the options so complex that staff at energy companies have no idea which is the best deal, according to an undercover investigation.
Consumer body Which? called each of the six major energy suppliers 12 times in one week to get advice on the cheapest deal.
Despite being asked clearly for the lowest cost option in each case, in nearly a third of the calls, the firms failed to offer their cheapest tariff. Staff also gave questionable advice about potential savings, cashback deals and fixed prices.
The big six energy companies have about 400 tariffs on offer between them, with some only available to online customers, others offering cashback incentives and others with "bill free" months if a customer signs up for long enough.