Alistair Buchanan, chief executive of Ofgem, said that the body's latest findings were evidence that energy suppliers need to continue to work hard to provide better services to their customers.
He explained: "With winter drawing in and all suppliers having lowered their prices, now is a good time for all customers to check whether they are getting a good deal."
Ofgem was established to protect the interests of energy customers in the UK and promote competition across Britain's gas and electricity markets.
The body has recently appointed a new director of European strategy and environment.
Martin Crouch said he was "looking forward" to taking up his new role, after moving from his job as the regulator's electricity distribution director.
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