Maybe your account was flagged as part of some multiple accounts. The things you want to first cross-check with are, if;
1. You have someone in your family who also opened a sportsbet account and uses the same internet connection.
2. You shared your device with someone else who created and logged into a sportsbet account.
3. You used a VPN service to register and log into your sportsbet account.
These are parts of their ToS
3.4 If you attempt to open more than one Member Account, we reserve the right to block, suspend or close your Member Account, as well as freeze any funds credited to your account.
8.6 Rewards can only be received once per person/account, family, household, address, e-mail address, IP addresses and environments where computers are shared (university, school, public library, workplace, etc.). The Company reserves the right to close your account and confiscate any existing funds if evidence of abuse/fraud is found.