To activate a self-exclusion, make sure you are logged into your account. Next, go to Account Settings > Deactivate Account. You can then select the time period for which you wish to self-exclude, and press save.
Once save has been pressed, you will be logged out of your account and your self-exclusion will have began.
Alternatively, you can reach out to BET99 Customer Support who will be happy to activate your self-exclusion on your behalf.
Please also note that once an exclusion has been activated, BET99 are unable to reverse it under any circumstances, even if activated by mistake, until the end date has passed.