You can’t do anything than wait for them if their reason of holding your account is due to investigation because it can take longer for at least 6 months for some casino as standard investigation time.

You can follow @acroman08 suggestion to provide screenshots so that user here can have a glimpse to your case and might help you to connect on the Rollbit reps here to make the investigation faster. 2 months of waiting is already too long now may @Razor can help you to get your funds while the current price of ETH is already skyrocketed since the time you made your deposit.