Any advice on selling codes you get from pre ordering games? I have sold a couple in the past and never had an issue. Today someone purchased a code from me and said when they tried to enter it, it stated it was already used. There is no way it was used unless amazon sent me a bad code which has never happened to me before. Any advice on how to handle this situation? Should I just refund his money? Also any advice for the future if I sell these digit codes again to avoid this type of problem? Any help is appreciated. Thanks.