My story is pretty similar to this one β The buyer bought the code and immediately filed a dispute. In the meanwhile, the code was also redeemed, according to an MS customer service representative.
The order id is d683db49-580d-4d7c-b6b5-ede8fb30664d .
Good news for you is that after 3 days when Gameflip find in your favour then the dispute is closed and you will be auto-rated positive and receive your money.
Can I suggest that you do the following:
Post your Invite Code
Attach a file/screen shot or using snipping tool produce an image of any correspondence/evidence to support your claim/issue.
PM the Moderators - DunnBiscuit or op_JOkEr (They do not work during the weekends so itβd be Monday before you likely hear anything back)