So I sold in-game coins to a player in an online game, a few weeks pass and he seems happy, he buys coins a few more times and I never hear from him again. Then word is he got banned from the game (for whatever reason, I am not aware) I do refunds but in exchange ofc, I want the coins given returned, but because he was banned there was no way for me to get the coins back, so I didn't refund his payment after he asked me. then he decides to open a case on the largest payment he made in one go, 27 dollars. He claimed that I had "taken the money in the game back" so he wanted his money back. I wasn't worried about that because it was a blatant lie however even after the explanation I gave about him being banned, the money was still given back to him, I don't really understand this, whether I broke any rules or terms, but it seems I got scammed? I don't really know what to do from here and any help would be appreciated.
