What if the user didn't really exploit the site? You've just mentioned that Crash game was just added recently and people don't play it that much (quoted message below). Isn't it possible that you missed to know/checked all of the bugs because you're thinking that only few are playing Crash?
Crash game has been added 2 months ago, to be honest, people don't play crash that much, 90% of players play dice. We have manual withdrawals, yes.
Anyway, I hope you could fixed the problem as soon as possible. Also, if there's no proof that the person exploit the site, you or the owner of bitcoingamesclub should pay him the won amount.