A mum was left shocked after energy giant EDF charged her £336,865 for one month's electricity.
Emma Martin, 40, was checked her account and while her monthly gas payment had remained the same, her electric bill had soared.
The dinner lady noticed while changing her payment plan.
Concerned about the extortionate cost, Emma said she tried to get in contact with EDF to explain the situation, but she was unable to get an answer.
When she finally managed to speak to someone on the energy company's online forum she was simply asked "would you like to split the payment over 36 months?"
Emma, from Hartlepool, Durham, said: "When I first saw that number I had a bit of a panic because it's not what you expect to see when checking your monthly bills.
"I instantly knew there had been a mistake but no one from EDF would reassure me the problem would be sorted out.
"When I called their phone lines they just cut out and on their online chat they replied around once every 16 hours.
"When I finally did get through to someone they plainly asked me if I wanted to split the payment over 36 months which was just mental.
"As you can imagine I was very concerned."
EDF said a mistake had been made.
A spokesperson for EDF said: "When setting up the Direct Debit online, an incorrect electricity meter reading was submitted which resulted in the higher monthly charge.
"Mrs Martin has never received a bill for this amount and we’ve now corrected the meter readings."
