A seven year old girl unknowingly ran up a bill of £250 on a Facebook game in front of her parents.
Megan Fox asked to play Petville, an online game where users can buy virtual clothes and furniture for a make-believe pet.
But dad Matthew, 35, had forgotten to log off from his stored PayPal payment details.
He later received an email billing him for 400 US dollars for Megan's games session.
Matthew and wife Dawn, 33, pleaded with Facebook and PayPal for a refund but were refused.
The couple, who live in Birmingham, don't let Megan have her own Facebook account so Matthew allowed her to log into his as he sat nearby.
Paramedic Matthew said: 'She was playing the game, asking which dresses we preferred. We played along, not realising she was actually spending money. I was mortified when I found what had happened.'
The site's rules say the account holder is responsible if someone in the household makes purchases.
Facebook said: 'We urge parents to take responsibility for their kids.'
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