In Malaysia, if someone is stalking you on the phone, and if you are using an iphone, you are not allowed to block that user, evebthough you know the number. If you are using an android, you can block that user.
Making a police report is useless because the police will tell you they cannot do anything since it is not life threatening.
Making a complain to your telephone company will not really solve your problem if you are using an iphone. The only solution recommended by them is to change your number.