apple id has been hijacked
they buy games coin from my apple id. what shoul i do?
You might want to consider changing your password and making sure it is a strong one. You can also add 2 Factor Authentication to your account for more security. If the attempts continue, you might want to consider a name change.
Note the restrictions in the article.
What to do after you change your Apple ID or password - Apple Support I suggest doing this before you change your Apple ID or password.
Apple ID -Two-factor authentication
Two Factor Authentification availability
Apple ID - Using app-specific passwords
Apple ID - Two Step Verification App Specific Passwords
Apple ID - Two Step Verifications FAQ