Please help, apple id hacked

Hello,

i could not find apple support number to call or email to write so i’m posting this here.

My brother’s Apple Id has been hacked and its blocked now, we still have the password and email control, but cannot login to appstore, it says that account is blocked in security reasons and to unlock it requires a phone number that we are not familiar.

What can we do to regain access and unblock the apple id? Any attempt to reset password or unblock the id leads to that phone number promt and we don’t know that phone number!