Don’t know if you have already thought of this but I would go after the parents – as owners of the property they are responsible for the behaviour of their tenants and guests.
Get your local paper involved – they will love the phrase “Brat-dumping” which is what we call privilieged parents forcing other people to live with the results of their lack of parenting skills.
Show them all the NTCs and warning letters and invite them to hear the music at its worst