Thousands of E.ON UK customers have accused the energy supplier of overlooking them after its customer service channels shut down for weeks after a major billing blunder, which left millions out of pocket before Christmas. During the winter’s coldest spell so far, many customers have been unable to top up their pre-pay energy meters, or contact the supplier to set up payment plans after being furloughed in the latest coronavirus lockdown. The supplier’s customer service phone line has asked people to “call us back next week” unless their query is an emergency, and its website and app have both crashed after a deluge of complaints from customers who were incorrectly billed twice last month. By Thursday afternoon many customers had still not received a refund after the supplier claimed an extra monthly direct debit from customers in the days leading up to Christmas, which plunged customers into unplanned overdrafts. Customers have turned to social media to warn that many will be left without lights and heating if they are unable to add credit to their energy meters online, or to request financial assistance. “The problems are far larger than just the direct debit debacle,” an E.ON customer said. “They’ve not been answering their phones since the 22nd of December, or the [webchat] messenger, or emails. Customers have been without power where pre-payment cards aren’t working. It’s the worst customer service ever.” “I’ve been trying to set up a payment arrangement due to being furloughed for the third time, have been unable to speak to anyone, and today received an email threatening debt collectors at my door. [It’s] very stressful,” the customer added. E.ON’s energy problems emerged days after new mandatory regulations came into effect in mid-December, which require all energy suppliers to offer struggling customers debt repayment plans or top-up credit if they are on prepay energy meters to help households through the coronavirus crisis. A spokesman for the energy watchdog, Ofgem, said it is crucial that suppliers ensure that their customers can “quickly get in touch with them when things go wrong”. A spokesman for E.ON said on Thursday evening that the company has repaid all direct debits taken in error last month and is “working hard” to bring on new measures to “resume normal service as soon as possible”. E.ON customers who are still struggling to top up their pre-pay meters can call the automated top-up line on 0800 015 6368 or the dedicated “pay as you go” support line on 0345 366 5995.