Households have been urged to "fight back" as they face the almost certain prospect of industry-wide energy price hikes.
SSE's announcement of an 8.2% increase is widely expected to be followed by its competitors, while watchdogs and charities fear that consumers confused by a complicated market believe they have little choice but to ration their heating.
Since the start of the century, the price paid by households for gas has more than doubled, while the cost of electricity has increased by 70%.
Energy bills are now at a record high of an average £1,315 a year. Prices have been rising at around 9% almost annually for the last five years while the profits made by the major companies have soared by more than 70% in that time.
National Debtline said it had received a record 15,502 calls from people seeking help with energy debts in the first six months of this year, up 10% on last year, and 111% compared with five years ago.
But consumer experts urged bill-payers to help themselves by seeking out fixed tariffs immediately, warning that they are likely to be pulled soon.
MoneySavingExpert.com founder Martin Lewis said there were still deals allowing households to lock in and guarantee no price hikes for up to four winters.
But he said: "Speed is of the essence."
He said: "Now's not the moment to simply use a comparison site and switch to another provider. You risk moving out of the frying pan and into the fire, possibly shifting to a firm that puts its prices up even more. If that's your plan best hold until all have announced."
MoneySuperMarket.com editor-in-chief Clare Francis said: "This news could make the colder months even more miserable, unless consumers fight back and fix their energy bills to protect against price increases.
"We really need to see a change in consumer behaviour when it comes to energy prices. After years of annual hikes, energy bills are one of the biggest outgoings for many households, yet most are still paying their provider's standard prices.
"It's an area where customer apathy is rife even though when it comes to switching to better deals - energy is one of the easiest ones to do."
Ann Robinson, director of consumer policy at uSwitch.com, also appealed to consumers "not to sit back and watch energy costs soar".
She said: "There are two simple steps to protecting yourself from the impact of higher prices: use less energy by making your home more energy-efficient, perhaps by taking advantage of the Green Deal, and pay less for the energy you do use.
"There is currently around a £250 difference between the cheapest and most expensive energy tariffs on the market. However this could increase to as much as £349 once SSE's price hike comes into effect.
"This is a substantial saving and could make the difference when it comes to keeping warm."