You said you deposited 0.3 ETH, which is approximately $500. I am trying to understand, how does the amount get to $5,000?
I am not going to share the links of the threads here, but if you look around, there are so many scam accusation and complaints about that casino. I still don't understand how you ended up using their service?
Anyway, here is a start
I am going to notify them about this scam accusation in their thread, and we see how they can solve this problem. Meanwhile, you can also send PM.