A barmaid has spoken of her disbelief after receiving a £90 million electricity bill from Midlands supplier npower.
Alison Turner, aged 50, of Cambridge, was stunned when the demand arrived through the post on Saturday.
The mother-of-two, who lives alone in a one-bedroom flat, normally spends about £20 every two weeks to top up her pre-payment electric meter.
But the letter, on npower headed paper, said: “We have checked your account and there is a balance to pay of £90,454,217. This is because your token meter was undercharging you because our prices have changed since it was last reset.”
It said the “balance was now due” and invited Ms Turner to contact the energy company to “discuss repayment options”.
Ms Turner said: “I know energy bills have gone up but this is ridiculous.
“It’s lucky they didn’t send this letter to an old-aged pensioner because they would have probably keeled over.
“Luckily, I was with my daughter and we knew it was wrong.”
Ms Turner said she switched to npower in November, but changed suppliers again four weeks later.
The company employs around 8,500 people and has its head office at Junction 6 of the M5 near Worcester.
An npower spokesman said: “We found the letter and what has happened is our eight digit account number has been inserted in place of the outstanding balance. It was a human error.
“When the customer contacted us, we immediately apologised and wiped the debt, which was actually £22.”