Make a scam accusation here and make sure you put all your proof there. Then email their support team and ask them if they are aware of said accusation and that their entire company will be branded as a scam if they do not resolve this.
Based on previous problems other users had with sportsbet (such as this*), that should be enough to get them to respond to you unless they want a red reputation.

*it seems the op has deleted his accusation. However, I've found the same accusation quoted by another user.