Households are being forced to choose between basic access to electricity and food, one energy giant has said.
Bill Bullen, chief executive of energy supplier Utilita - which serves prepayment meter customers - said the government needs to tailor its emergency support to those who are struggling the most.
He said ministers should spend money on "insulating the hell out of Britain".
Millions of households are facing a 54% rise in the cost of a typical annual gas and electricity bill, to about £2,000, from April 1 when the price cap rises.
The war in Ukraine is also threatening higher prices from October, as sanctions pile pressure on gas supplies.
In response, households have been offered a £200 energy bill rebate, but the support has been slammed as a 'loan' because it must be repaid over five years.
The government's cold weather payments scheme is also about to close for the year and while the £140 warm home discount is rising to £150 this winter, around 200,000 disabled people will be kicked out of it.
One of the last few remaining options is for households to apply for an emergency grant from their supplier.
Even consumer champion Martin Lewis has said he's running out of advice for people who are struggling.
Mr Bullen said the price rise was inadequately focussed, leaving millions of people facing tough choices on their family budgets.
"They just do not have the money," he said.
He said that the "path of no regret" for the government was to find ways to cut energy consumption, and therefore bills, over the long term with a massive home insulation programme. It was relatively easy, he said, to cut consumption by 20%.
The price rise for prepayment meter customers, who can include some of the poorest and most vulnerable in society, is slightly higher. The increase for prepayment meter customers is typically £708 a year.
Ahead of the Spring Statement, a string of charities have called on the chancellor to step up support for those struggling to pay their bills, given the rising cost of basics such as food and fuel.
The debt charity Christians Against Poverty said calls to its helpline went up by 47% in January compared with the same month last year.
The Joseph Rowntree Foundation argued that the minimum requirement from the chancellor to tackle the cost of living issue was to increase benefits in line with inflation - close to doubling the 3.1% increase set for April.
All eyes are on what the Chancellor will deliver in his mini Budget this week.
Concerns over energy security have fuelled calls for more domestic production.
Some ministers want fresh investment in shale gas, or net zero rules relaxed for North Sea oil or coal-fired power. Labour want a windfall tax on energy producers, which have benefited from high prices, with the proceeds earmarked for supporting vulnerable families.
Other possibilities include making the £200 energy rebate optional, doubling it to £400 or extending the repayment period past five years.
Meanwhile, surging oil prices since the Russian invasion of Ukraine have sent the price of petrol to record highs.
Backbenchers are pushing for a tax cut. Fuel duty is 57.95p a litre, plus 20% VAT. The Conservatives have frozen fuel duty for 12 years but campaigners say this clashes with net-zero ambitions.
