I'll try to be neutral here.
OP, sending coins to the wrong chain is your fault (not blaming you or anything as we all can make mistakes) and it has nothing to do with the hot/cold wallets set up as you suggested. Still, this doesn't give the casino the right to keep your coins hostage and they should help you recover them, if possible.
However, you should know that recovering coins sent to the wrong chain isn't as easy as some might think and it may has some security implications (exposing private keys).
Also, most services will simply refuse to help in such cases and some of them require paying a fee and even then, the process may take up to few weeks.
Anyway, I hope your case will be resolved asap.
Indeed its not going to be easy to recover a coins sent to the wrong chain and its clearly op's fault for not double checking.
Now he is seeking help for Bitvest team, but as we know they are not really responsive and case similar to this is hard to be resolved.
Anyway, op is aware of the casino's reputation (he has an issue even before) so im wondering why he still choose Bitvest to play in.