as far as I know they have 3 providers, and if there were any problems as you say with arbitration situations, then the provider would have stopped this moment, from this it follows that the casino allowed itself to simply zero out my winnings, because it did not want to pay them out
What I’m trying to suggest is seek help with casino guru or askgambler because they can look closely on your case provided that you are innocent since they can ask the casino with supporting documents about their decision to ban your account.
Maybe @holydarkness can help you since he has connections with multiple casino representatives. I’m not trying to be negative here but issues that involves violation of ToS is very to win against casino.
Just accept their refund first then pursue your case.