Hmm, I am not siding with bookmakers in general, but I don't think you are right here. These anti-multi-accounting rules are for bonus abuse, promotion abuse etc, but also to get rid of unprofitable customers. So in your case, Sportsbet made clear, that you can still bet there, but with lowered betting limits. You bypassed this restriction with opening two new accounts, so technically I don't see nothing wrong with them not paying you. Nobody reads the T&C, but you should at least know, what normally is stated there and you will find multi accounting being forbidden in nearly every bookmaker. So if you violate these T&C, you can't say they scammed you, since you accepted the T&C by registering.

If this all makes sense and is fair, is another story then.......