A mum-of-three said she was horrified to get an energy bill for almost £2billion - for just two weeks' power use.
Brenda McCossick got the bill from Shell Energy, which told her she owed £1.9billion.
Brenda, 50, is a police call handler and lives with her daughter, who is 15, The Sun reports .
Her usual energy bills for her three-bedroom detached house are around £50 a month.
She said: "I knew the amount is going up given the rise of energy bills but I couldn’t believe it.
“It must be a record for the biggest energy bill ever.
“I usually turn off the lights when we leave a room and make sure we are as eco-friendly as possible so I knew it couldn’t be right.”
Shell later apologised and corrected the bill - to £46.
A Shell Energy spokesperson said: "This was an error in our app that affected a small number of customers, and we don't expect Brenda to pay for the world's supply of gas.
"Any customers with the same app error can be assured that it won't have any impact on their direct debit payments."
However, this sort of massive overbilling error by energy firms is not new.
The Mirror has spoken to a woman, now 80, who was given a £1million energy bill by British Gas - back in 1980.
The woman said: "I just laughed when the bill dropped through the door and quickly rang British Gas to tell them of their error.
"It was a young girl I spoke to who officiously told me that if that was the amount shown on my bill, then I would have to pay it.
"We then had an exchange of a few choice words and I still recall telling her she should take my number down and get someone with a bit of intelligence to call me back.
"Someone did call me back and it transpired the meter reader had transposed two digits and so the meter clock had gone right round and back again.
"Shortly after that I received an amended bill together with an apology but no offer of compensation."
Energy bills are rising, and are due to increase by £693 a year for the average household from April 1.
The cost of the average variable rate energy bill, for the average household, is capped by regulator Ofgem.
That cap is rising from £1,277 a year to £1,971 on April 1, with further rises expected from October, in response to supply demands due to the war in Ukraine.
The good news is that there are some schemes that can help.
Many energy companies have launched hardship funds to help customers with rising fuel bills and associated debt.
For example, British Gas has launched its British Gas Winter Fund, which gives eligible customers up to £750 toward the cost of their energy bills.
British Gas says the average payout per grant so far has been £510.
Other similar grants include the Ovo Energy Fund, E.ON Energy Fund, Bulb Energy Fund and the EDF Energy Customer Support Fund.
Energy providers can also set up payment plans to help customers with bills.
Elsewhere, the Warm Home Discount is available to some people on benefits with more information available at Citizens Advice. The scheme could help you take £140 off your bills.
Shelter also provides information to help people struggling to pay their energy bills - it can give more details of the Warm Home Discount and explain what you can get dependent on your particular circumstance.
Anxieties about the cost of living are common and fears over how to look after your loved ones can take a toll on more than just a bank balance.
If you feel you need extra help, charities like mental health outfit Mind can be a great way to help with your wellbeing.
