something like that happened to me at an auction, I bought a nice large clock and they carried it to the back near the check out and i just happened to look back a few minutes later and see a guy trying to leave with it. Jumped up and ran for the door and he said he bought it, lady behind the window says he said we did not hear the bidder number right and it was his.I gently took it out of his hands and paid for it and told him he needed to get a refund

Remember you are only as good as your help
If you don't make any noise no one will hear you!