neighbours from hell

My wife and I recently bought our home in a known family friendly area in Sydney's south. We have one child who is about to turn 4.

Unfortunately our house and lives are being ruined by terrible neighbours. Our neighbours are three 20 year old big blokes who listen to loud music at all hours and get drunk pretty much every 2nd night on their back porch. They live rent free in a 2 storey 4 bedroom home owned by one of the blokes parents. They treat it like a frat house. We have spoken to the other neighbours who all can hear the music and swearing but I think they are too intimidated to do anything. We found out the people we bought our home from actually sold because of the neighbours, and they had been in the house for 40 years!

The police put a 28 day noise abatement order on them a couple of weeks ago, but lo and behold on Sunday morning they stumbled home and proceeded to play music at loud levels from 4am to 6:30am. I rang our local police but was advised they were too busy with other jobs to come out to tell them to turn it off. I rang the police again today to enquire if there is anything else I can do but they said they cannot enforce the noise abatement order without actually being out there and witnessing it themselves. The police have only turned up about 20% of the time when we call, and half the time they just pop in for 1 minute and the neighbours turn the music back on 20 minutes later.

I have spoken to the neighbours who play dumb and say their music isn't that loud. I have it on video how loud it is. I'm trying to find out where the blokes parent's live who own the home to see if I can speak to them.

It is causing a lot of stress for me and my wife, even to the stage where we are contemplating selling our home despite only buying it 4 months ago. Life is too short for this much stress. Once after the police actually did turn up the neighbours chanted "Welcome to your new home, got suck a fat one". So it is starting to get a little aggressive. They swear profusely and right outside my son's room.

Has anyone had similar experiences, is there is anything else I can do?