The poorest and most vulnerable people in the UK risk missing out on the energy bill support and cost of living payments they are entitled to, because of a lack of clarity over what is available from the government and how to get it, charities have warned. Under the energy bills support scheme announced by Rishi Sunak when he was chancellor, all households are eligible for a £400 energy bill discount, paid across six instalments starting last month. Most customers should have the discount automatically applied, while those on traditional prepayment meters are supposed to receive either vouchers or automatic credit at top-up points. But the charity National Energy Action (NEA) says there is a “significant risk” households on older prepayment meters will not be able to redeem vouchers, some of which it says have been addressed with the wrong name, or with incorrect details. Meanwhile, food bank staff have told the Observer they are seeing significant confusion over both energy bill support and the £650 cost-of-living payment – supposed to be paid in two instalments to those on low-income benefits and tax credits. They say that many have not received the payments they are entitled to. The warnings come as government data shows 42% of vouchers for customers with older prepayment meters have yet to be redeemed, according to NEA, warning that this could be an “alarming early indication that those most in need could miss out.” Peter Smith, NEA’s director of policy, said these households faced “significant challenges accessing this government support, despite being at acute risk”. “We’re finding vouchers are being sent out with the wrong name or incorrect personal details. Because [in-store payment service] Payzone aren’t taking part in the scheme, some customers are having to travel long distances to access support,” he told the Observer, adding that the charity was urging people with older meters to contact their suppliers themselves. He added: “We are also talking to government about what contingency could be made to ensure these customers get equivalent support if the redeem rate doesn’t improve before the end of March, when the scheme is due to end.” Charlotte White, manager of Earlsfield food bank in south-west London, said it had had to help numerous people – many of whom did not have internet access and were sitting at home in the dark wearing coats – to get their payments. “It’s quite confusing, so a lot of people are going to be turned off and it’s really frustrating when the onus is on people themselves,” she said. “It’s not just what support is available but it’s how easily and readily people can access that support that’s really important.” The problem is not simply choosing eating versus heating, she said, but the fact that many people are having to significantly ration their electricity. People, she said, are “sitting in the dark, sitting with blankets on, limiting the rooms of the house that they use.” One woman she spoke to this week was sleeping in her dining room to conserve heat, White said. Citizens Advice also reported three main problems with people trying to use vouchers for traditional prepayment meters. “People are confused about the support that is on offer this winter; people have not received their vouchers in the post; and people can’t use the vouchers where they top up, for a variety of reasons,” the organisation said, calling for more targeted support. “We have also heard from local services that some people aren’t cashing in their vouchers as they are saving them for later in the year when it’s colder.” The Department for Business, Energy and Industrial Strategy said all October’s and November’s vouchers had been sent out: “If customers have not received them, or are having difficulties in redeeming them, they should contact their supplier. “We appreciate some customers need to travel to redeem their vouchers … Customers should be assured that each monthly voucher is valid for 90 days and even in the event that they haven’t redeemed a voucher within the 90 days they can speak to their supplier as the voucher can be reissued.”