If you haven’t already done so, contact Gameflip support about this problem and put the transaction on hold so that the countdown timer is paused. Also, have you talked to your seller about this? Giving them the benefit of the doubt, maybe they sent the wrong code or they mistype something in the code. If they say it is a valid code and you say it isn’t, you will have to provide evidence. Go to the PSN website and talk to a representative through online chat and have them verify where and when the code was used or if it was ever valid to begin with. Have them confirm through chat the details of the code the seller provided you and then screenshot the WHOLE conversation with the web address and everything so that you can provide it as solid evidence to Gameflip support. DO NOT edit the picture(s) in anyway. Good luck and I hope this helped.