Independent figures seen by the Mail on Sunday newspaper apparently show legions of beleaguered households have switched supplier in the wake of soaring energy costs.
The data shows an average of 100,000 customers swap their Big Six energy provider for an independent firm every month since June last year.
The UK's Big Six group of energy firms are npower, SSE, EDF, E.On, Scottish Power and British Gas, and supply around 95% of the country's power.
They have come under fire in recent times for raising prices and now face a Competition and Markets Authority probe to see if there is enough competition in the UK energy market.
The latest official figures from the Department of Energy and Climate Change show that 1.3 million electricity customers and 866,000 gas customers changed supplier in the final quarter of 2013.
But figures in the Mail On Sunday state 2.05 million customers now get their energy from smaller firms, reckoned to save each customer around £200 a year.
The data covers electricity switching only, but about 80 per cent of those who swap electricity switch gas, it said.
Currently, switching takes around five weeks, which includes a statutory two-week cooling off period that came into force in June.
That time will be cut in half to two-and-a-half weeks under plans put forward by energy regulator Ofgem.
The proposals, agreed by the energy industry and due to come into force on December 31, will see switching times come down to three days plus a 14-day cooling off period.
Last month SSE said it lost 110,000 customers over the last three months, taking its base down to nine million despite freezing prices, although Scottish Power said its overall figure of 5.6 million customers was the same as December and June last year.
Earlier this week Centrica, which owns British Gas, said customer numbers had fallen by 1% over the first quarter before stabilising.
According to the latest figures, the Big Six suppliers received a total of 1.7 million complaints in the first quarter of this year alone, against a backdrop of crippling price hikes.
The figure is up from 1.48 million complaints in the same period last year, consumer group Which? said.
Energy Secretary Ed Davey said: "We have almost trebled the number of small suppliers since 2010 and our reforms are making it easier and quicker for people to switch energy suppliers - around two million consumers have switched to independent suppliers since 2010.
"Households could save £200 a year or potentially more by switching supplier, and we encourage all consumers to shop around for the best deal for their energy bills."
A spokesman for trade association Energy UK said: "Figures show people are taking advantage of competition in the energy industry by switching supplier.
"There are now more than 20 suppliers that customers can chose from.
"We encourage people to shop around to make sure they are on the best tariff for them. We are making it quick and easy to switch supplier so people can readily compare one tariff with another."