The number of people switching energy provider spiked after British Gas said it was planning to hike prices.
Figures by price comparison site Comparethemarket showed a 150 per cent spike in consumers changing energy providers, compared with the week before.
Of those, nearly half were British Gas customers looking for new energy providers, the website said.
The surge came after Centrica, the owner of British Gas, said at the beginning of this month it will raise the price of electricity by 12.5 per cent from the middle of September.
The price hike will mean the average annual duel fuel bill for a typical household on a standard tariff will rise by £76 to £1,120.
The company said it hadn't raised prices in "nearly four years", but had been spurred to do so by the rising costs of electricity.
But today Peter Earl, head of energy at Comparethemarket.com, said the move was the "final straw" for many of British Gas' customers.
"[It] was a clear illustration that loyalty simply does not pay in the energy market.
"The fact that savings of around £290 per year can be achieved by switching energy tariff is a real indication that pricing in the market is dysfunctional.
"The activity on our website shows that consumers are voting with their feet. The Big Six energy companies have a huge job to do in terms of rebuilding trust. If they don't, the stampede towards the challenger brands will only accelerate."