Cordog418888 has agreed to buy me the Supreme Rank upgrade and alleged to have bought it and the rank is not coming, he supposedly tried 3 times and still has not come in. I instructed Cordog418888 to post a receipt in the comments or deal with a ban. @Musezeta
Do you have any screenshots of either in-game chat or from the game output on the launcher of him either leaving or saying it doesn't work and not paying you back? Also allowing for 24-hour buycraft grace period.
Try checking your game output data in the launcher if you keep it running at all times (which I suggest doing, as it records all chat)
For future reference it is best to get proof of: What the deal is Payment Whether or not the player left, is ignoring you, or any other form of communication that would state they are not going to proceed with their part of the deal If you happen to have any more evidence you may post it, otherwise I will have to close the thread due to lack of evidence.