A couple were shocked to come home to find an energy company they are not customers of had changed their locks and installed a pre-paid meter inside the house.
Rachael Holgate, 24, and her partner, who own their property, were locked out of their home for four hours in Hull.
They say they felt "sick" and "humiliated" to know someone had broken in without their knowledge.
They also say they are now "stuck" with a pre-paid meter with no account and no idea how to top it up.
It is understood the error came from a case of "erroneous transfer", which is when an energy company takes over the wrong account, HullLive reports.
SSE Energy, the company behind the mistake, has since apologised.
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Rachael has always been a customer of Shell and had never defaulted on a single energy bill.
They initially started to receive letters from SSE Energy that were addressed to another man, but always returned them to the sender assuming the company had the wrong address.
Then bailiffs turned up at their door with a warrant obtained by SSE Energy (now run by OVO Energy) to install a pre-paid meter within their home.
The warrant was addressed to the other man, and the bailiffs apologised and gave a customer service number when the couple explained that man did not live there.
Rachael said she spent "hours" on the phone with operators, but because she didn't have an account with them, SSE couldn't discuss the case.
She added: "I must have been on the phone to customer service for hours to try to sort the mistake, but because I wasn't a customer, they couldn't discuss any account with me due to data protection.
"They couldn't even make a record of anything because there was no account to make notes on, so I had to explain myself over and over again."
Rachael said one evening she came home from work to find her partner sitting outside the house.
Their locks had been changed and a note on the door said it had been done by the "energy supply company" and they should call a number to get new keys.
She said there were locked out for four hours before someone let them in.
Rachael's partner works as a bricklayer and had to miss one of his jobs that evening because he couldn't get his tools from inside the house.
When they got inside, they found a pre-paid meter, with exactly £4.72 credit, had been installed in their cupboard by OVO Energy.
Rachael said: "With the price of energy nowadays, we are in such an awful position now. For our neighbours to watch bailiffs break into our property is absolutely humiliating, when we have done nothing wrong."
She decided to do her own digging to find out who the man on the warrant was, as she knew the previous homeowners did not share his name.
Taking to Facebook, she found a man from Hull with the same name and asked if he had ever lived at her address. He said he had lived down that street, but never at that particular house number.
The couple is now going through the Energy Ombudsman to remedy the mistake, which they say has left them feeling uncomfortable in their own home.
SSE Energy (OVO Energy) advised it may take up to 15 days to get back to her and she is having to use the meter in the meantime. She has also contacted the police.
A spokesperson for SSE Energy Services told HullLive: "We’re very sorry to Mrs Holgate for the inconvenience caused. We’re attempting to reach Mrs Holgate to apologise and provide a resolution"
It is understood Rachael was the victim of an erroneous transfer where an account is transferred by mistake - which can happy when a customer accidentally selects the wrong address.
It is understood that the error should have been noticed after Rachael contacted SSE Energy to explain the customer did not live at her address.
However, as this was not followed up, bills continued to be sent to her address.
Shell Energy, the couple's original supplier, was contacted for comment.
The Mirror contacted SSE Energy, OVO Energy and Shell Energy for comment.
