- 8 updates
The main suppliers, known as the Big 6, control 90% of the UK's energy market today stand accused of making a huge profit from the less well off.
The investigation, by the Competition and Markets Authority, found millions of dual-fuel customers, many of whom have never switched suppliers, have missed savings of up to £234 a year.
ITV News Consumer Editor Chris Choi reports on why loyalty doesn't pay.
Richard Lloyd, Executive Director at Which? told ITV News that the report is: "a damning indictment of how competition is letting customers down. It's proved that the politicians are wrong to hope that competition will fix the massive problems in the energy market."
ITV News' Consumer Editor Chris Choi says a chart released by the Competition and Markets Authority, as part of its update on pricing in the energy sector, seems to be the "smoking gun" that shows the growing separation between costs for companies and what they charge customers.
Energy Secretary Ed Davey has reiterated his advice to energy consumers to "shop around for a better deal, switch suppliers and save".
Mr Davey was responding to an update from the Competition and Markets Authority into pricing in the energy sector which said loyal customers could save up to £234 by switching.
An update on the investigation by the Competition and Markets Authority into the energy sector has found that the number of people switching suppliers is at an 'all time low' despite the potential savings.
However ITV News' Consumer Editor Chris Choi said the CMA report offers no ideas on how this issue can be addressed.
Labour's shadow energy secretary Caroline Flint said an update by the Competition and Markets Authority into pricing in the energy sector which criticises the amount loyal customers are charged, proves "Britain's energy market is broken".
She added: "Radical action is needed to protect consumers. Energy bills are £300 a year higher under the Tories, and David Cameron has let the energy companies get away with overcharging millions of consumers.
"That's why the next Labour Government will freeze energy prices until 2017, so that bills can fall but not rise, give the regulator the power to force energy suppliers to cut their prices and end overcharging once and for all."
A competition probe into the energy sector has found that 95% of dual fuel customers who stay loyal to the Big Six firms are routinely charged up to £234 more a year than those who switch.
The Competition and Markets Authority (CMA) revealed part of its findings into pricing in the sector today, after an official inquiry began last year following a referral by Ofgem in light of soaring household bills and increased public distrust.
The CMA's full provisional findings will be published in May, but a summary of evidence gathered to date was released today.
The update revealed that the vast majority of customers who receive all their energy from one supplier could have saved as much as £234 a year between 2011 and 2014 if they had switched firms.
This affects the some 40 to 50 per cent of people who have stuck with the same supplier for more than a decade.
Evidence from the probe also supports the suggestion that the so-called Big Six companies "segment the market and price discriminate".
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