Energy UK on fuel bills and cost of gas and electricity
Christine McGourty of Energy UK said companies were writing to people urging them to shop around but was asked why they were not automatically putting customers on the cheapest deals.
She claimed: "People like choice: not everyone wants just the cheapest tariff, it is not as simple as that."
She said the energy firms were not making excessive profits - and their margins were less those earned than supermarkets and telecom companies.
Labour's energy spokesman Luciana Berger was challenged on the party's record of combating high energy prices.