Energy consumers should vote with their feet and leave suppliers who offer uncompetitive prices and poor service, according to the Energy Advice Line.
The advice follows news that Big Six supplier SSE has lost 110,000 customers in just three months despite a pledge to freeze prices.
Julian Morgan, managing director of the price comparison, switching and advice service, said households were finally beginning to demand more from suppliers.
"Business and domestic energy users are beginning to realise that they don't have to stay with suppliers they're not happy with," Mr Morgan said.
"There's still a long way to go in terms of numbers - sadly the vast majority of consumers don't switch - but these SSE figures illustrate clearly that unhappy customers do have options.
"The UK energy market is not as competitive as it should be but that's not to say consumers don't benefit from switching suppliers. They do, often by very significant amounts."
SSE blamed "very competitive market conditions" for the drop in customer accounts, which fell from 9.10 million to 8.99 million in the three months to June. The loss comes after 370,000 customers deserted the supplier in the year to March.
SSE raised its electricity prices by over 8% last October but promised in March to freeze prices until January 2016.
"SSE clearly lost the confidence of it's customers by raising its prices by an unreasonable amount last year. Those customers weren't going to be won back easily," Mr Morgan said.
"This is a lesson, not only for SSE but all the big suppliers, that customers aren't stupid and are in fact becoming more savvy when it comes to energy supplies.
"They're demanding a better deal in terms of both price and service and some are prepared to switch suppliers to achieve that end.
"Those customers who did leave SSE will have learned that there are substantial savings to be made by switching, and that it wasn't as difficult as they might have feared."
Mr Morgan said that switching was one of the simplest and most effective ways for households and businesses to reduce their energy bills was to ditch their old tariff and switch to a new supplier.
He said the savings could be significant, especially for those who had not switched before or who had been with their current supplier for some time.
"Many customers we help are surprised at how simple the switching process is. They think it's going to require reams of paperwork, correspondence, meter readings and headache. Actually nothing could be further from the truth.
"A reliable and independent switching service like the Energy Advice Line actually does everything. After we find a customer the cheapest deal available and take some details, there's actually nothing else to do.
"We organize the switch from start to finish and it happens seamlessly. And the best part is that it's completely free."
The Energy Advice Line actively campaigns for reform of the UK's energy market so that businesses and domestic energy consumers get a fairer deal and cheaper prices from the major suppliers.
It also offers a free and independent price comparison and switching service that enables consumers to shop the market for the cheapest energy deals with the click of a mouse. For further information visit Energy Advice Line