I've never sold anything on GB but I doubt the high bidder can do anything but complain. And by the way, the bidder should be big enough to step up to the plate and admit his winning bid was a fluke. Sometimes adults just have to act like adults and get over it.

"The universal aptitude for ineptitude makes any human accomplishment an incredible miracle." John Stapp - "Stapp's Law"
"Klaatu barada nikto"