A "dossier of disgrace" was compiled by the country's biggest trade union showing the "greed" of energy firms as part of a campaign for a windfall tax on company profits.
Unite said that since 2003, energy firms have increased their profits by 538% to £3 billion and raised prices by up to 35% this year alone.
The industry was spending just £50 million a year combating fuel poverty despite the "huge" hikes in prices, profits and share dividends, said the union.
Joint leader Tony Woodley said: "The greedy oil companies have made tens of billions and in the next four years they will make an extra £15 billion from the British public.
"The Government must intervene now. Our case for a windfall tax is compelling. It is morally right. I say to the Government it's time to do the right thing and protect the most vulnerable in society."
Derek Simpson, join leader of Unite, added: "Winter is approaching and in the coming months low paid families will be forced to switch their heating off because they won't be able to afford the bill.
"The heartless excuses from the energy companies for not fulfilling their social responsibilities have been swallowed hook, line and sinker by the Government. It's time for action because the situation is dire."
The dossier said energy firms expected to make billions of pounds in windfall profits over the next four years.
Companies paid £1.6 billion to shareholders last year, up by a fifth on the previous 12 months, said Unite.
The report added that the percentage of profits spent on finding new deposits of fossil fuels had remained flat for years.
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