Maybe because I haven't created multiple accounts, thus not violating their rules? If they are so sure I have opened multiple accounts, why don't they tell me the usernames of "those" accounts?
Then you're either playing from a VPN or something else that they constitute "multi accounting." Maybe you created another account and don't remember?
They aren't trying to steal you supposed .304 BTC.
That's nothing to a multi-million dollar operation like Sportsbet.io.
That's not how scam sites work.
Regardless, you 4 forum posts are dedicated to bashing Sportsbet.io, which in my opinion is one of the most legit Bitcoin sportsbooks.
Since you received your initial deposit back, I'd consider this resolved because they technically didn't have to give you anything back at all once you've been labeled a cheater.