A family who sent their home computer away for repairs were left stunned to receive back a different laptop - full of files detailing how to set up an illegal cannabis farm.

Stacey Knox sent her £399 laptop, used mainly by her young children, back to manufacturer Gateway on January 19 after it developed a fault - but it was stolen during a raid on the firm's repair centre in Manchester.

The company, instead of telling her what happened, sent back a different laptop, which included a step-by-step guide to dealing in drugs, from equipment and cultivation to lying to police officers.

Mrs Knox, a sales assistant, 27, married to hotel manager Lewis, 25, called Gateway immediately after turning the computer on, and said she was told they had decided to send her a different laptop from the depot after the robbery.

The couple, who live with their children Kyra, six, and Joshua, two, in Davison Street, Newburn, Newcastle, bought the laptop in September from Toys R Us in Gateshead.

But they feared being left with no computer and no refund after both the store and the manufacturer appeared to refuse to take responsibility for the mix-up.

Mrs Knox said: "When I turned this computer on, it had somebody else's name on it and then I found the guide to growing cannabis - how to get your own equipment and every step up to selling it. There were more than 100 pictures of every different kind of cannabis, guides on how to avoid being caught by the police and what to say if you're arrested.

"The children use the computer more than Lewis and I. If I hadn't turned it on, Kyra would have opened it and found all this."

Gateway told the couple to return the laptop and issued them with a code authorising its return, but when they took it into Toys R Us, staff initially refused to accept the computer and said they would have to hand it over to Northumbria Police.

Mrs Knox said: "I asked Gateway how I get a refund if the police take this away. They said 'That's not up to us', while Toys R Us were saying it was up to Gateway."

Gateway have now offered the family a full refund or replacement laptop from Toys R Us and apologised for the mistake.

Mrs Knox added: "After the initial mix-up, Gateway were actually quite helpful, but we weren't very happy with Toys R Us, who initially refused to give us a refund and called the police."

Gateway UK country manager Sarah Shields said: "This was an extremely bizarre incident, which was obviously totally unacceptable.

"We have extremely stringent protocols and processes, so we can trace this particular notebook back to everyone who has touched it and we are doing this now.

"We take this incident very seriously and anything like this goes straight to the top of our priority list, as we pride ourselves on excellent customer service.

"We have offered the family who bought this laptop a full refund or a replacement notebook and have assured them this will be looked into with the utmost sensitivity and security."

A Toys R Us spokesman added: "Clearly we apologise for any inconvenience caused."

A Northumbria Police spokesman said: "We have had a report of a laptop containing information about drugs being sent to a woman in Newcastle.

"We are making arrangements to visit the store where it was purchased and examine the computer."