Ive actually been through this whole process myself mate, in the end, if it bothers you that much all you can do is change your number. Either that, just put up with it until the person gets bored.

I had this going on about a year ago, I actually has a suspicion on who culpruit was. I contacted Telstra and they said that they can't do anything about it, and they suggested calling the police as by law, they cannot provide any information to me on the caller.

After speaking to the police, they said to log all the calls etc. but in reality, there is very little to be done unless the person has threatened in any way. If all they have done is ring and hang up it would be very difficult for them to get approval for a court order for Telstra to hand over the required information.

Honestly mate, if they arent threatening you or anything, best option is put up with it, sucks I know, but the person will get bored eventually.