I agree with Themas: Environmental Health at your Local Authority about noise or police about criminatlity, failing that go see a solicitor and get them to write to the landlord, they are better placed than you to track them down. Same thing happened to some people I know, the neighbours were so scarey no-one in the area would complain about the noise - we thought there was a street party going on when we heard it! My friend's solicitor wrote to their landlord and the noise stopped instantly, no problems since. Some people are so self- obsessed they don't realise the nuisance they cause to others.