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Did you lose the 0.15 before your last deposit? No casino would give you a refund if that's the case. Sounds unfair since they should have never allowed you to deposit in the first place but that's like the current standard.
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But I think it's fair to return all the deposits to me. And imagine that I never came to play again.
I've never seen a casino refund lost bets to players and I believe you are well aware of that already. You can try other medium like submitting your case to casinoguru or askgamber but I really doubt you will get a better result. You can still file a complaint in those platforms if you insist or you should probably just move on.