Yea, I'm not sure what the repercussions are for refunding purchases on various payments providers (IOS in this case), but players who are adamant will find a way. Like I've said, Philippines users have by far been the most abusive for me. A new method they've been abusing is finding stolen credit card numbers online and making huge in-game purchases with the stolen card numbers. Then a few days later, all those payments get refunded by the actual card holder, meanwhile the fraud player has distributed his massive amounts of in-game items to all his friends and other "secret" accounts. So I have to go through what database history I have and try and remove those purchases from all accounts they were distributed to, as well as username and IP banning ALL of those accounts involved in the whole scheme.
I'm not sure what type of game yours is, but because of these players I limit the level at which you can purchase virtual goods. This means these cheaters can't keep creating new throw away accounts as easily if they have to wait until level 50 to purchase the real money items. Really, I do whatever I can to try and see what patterns these cheaters use, then I put checks in place to try and stop them (or at least slow them down).