Hello, I have read your whole situation and I will start by saying that I am sorry that you are in it and that unfortunately we do not deal with sports betting as we do not have any experts in it. 

When I read the reason given by the casino for the void wins, it makes me think that they may suspect a multiple accounts problem. But let me ask you, what exactly is mentioned in the points mentioned by the casino? 

Anyway, I would definitely try eCOGRA if you think you haven't broken anything because it might have some impact. If you feel like going down the lawyer route, I wouldn't be surprised if you're convinced that you've done nothing wrong, but then again, that's probably going to cost you something. 

So that's what I would do to start with and see what happens.