Like I said earlier, are you sure you weren't hacked in some way. Either you re-used the same username and password on a different website or you got some malware on your computer? Windows 10 is full of bugs and malware.

There is a chance that someone got into your account, tried to withdraw your BTC, and when it failed due to the empty hot wallet, they got pissed and just made you lose all your BTC by betting until all was lost.

Maybe the admin can provide some log which IPs were used to login to your account. Did you use 2FA? Are you sure your account was secure?

Because if they were to scam you, why remove your balance why not just leave it in there and just not pay you? Also why even give you the 0.25 BTC bonus if they were a scam?

I think you might of gotten hacked or something.