An online auction for a five-year-old Wispa bar has been called off after the winning bid was declared void.
Wispa bars were brought back in October as a trial
Rebecca Wells, 17, from Stoke-on-Trent, put the out-of-date Cadbury bar up for auction on eBay after finding it down the back of a sofa.
The student said she was disappointed when eBay emailed her to say the top bid of £2,550 was unauthorised.
She was hoping to raise money for the charity LAM Action, which funds research into a fatal lung disease.
Birmingham firm Cadbury stopped making Wispa bars in 2003. It brought them back as a trial in October following an internet campaign.
"The person who won was either messing about having a joke or had their account hacked into," she said.
Ms Wells said there had been an earlier bid of £1,067 and she was waiting to hear from eBay whether the auction could be resumed.
Ms Wells said she initially wanted to eat the chocolate - which was best before 28 April 2004 - when she found it.
She said: "I didn't know what to do with it. I was looking for things to put on eBay when I found it so I thought I might put it on eBay and see what happens."
Ms Wells said she wanted to raise money for LAM Action because her friend had the disease and she wanted to help fund research into treatment.
Peter Bonner, who led the Bring Back Wispa campaign, said the auction might appeal to be people who wanted a memento from their childhood.
He said he thought it might sell for as much as £50.