First, have you told neighbours? You really should. It might be hard but you need to.
It’s my experience, see my post above, if you go to the police with a few bits of film showing the behaviour (you are allowed to film but not record sound without permission) make the police watch it, insist on leaving with an Incident Report Number, they may talk to this person forcefully.
If you can’t get them to do anything, ask to speak to the Community Relations Office (in NSW at least every police station is supposed to have one) and tell them you really need help.
If they are still reluctant, tell them you are going to complain via a Complaints Form (P964 I think, look it up anyway) and identify by name all of the police who haven’t helped you. A copper told me NO COPPER LIKES TO HAVE A COMPLAINT MADE AGAINST THEM.