Coachgmll:Any advice?
don't back out of a coin room once you enter - even if you see a matchup you don't like - if you don't play the match coins are still withdrawn.
OR if you get tired of waiting and exit or try to return to the menu - it is possible you were already matched up - but didn't see it before you clicked as it had not loaded on your screen yet.
the above scenarios are far more likely to have been the cause of players losing coins - than something completely random - that was not initiated by the player or an opponent.