me and my partner were in an almost identical situation going back 5 years ago now. We moved into a council flat above a woman (her boyfriend wasnt living there but was there so often he may as well have been) we learnt about their "story" from neighbours, the police and people who were once friends of theirs. They had lived up in the valleys and with a group of others had attempted to make their own LSD, it went wrong and those who used it ended up with serious mental health issues (dont know exactly what but do know the effect it had on them), fast forward and they moved into the downstairs flat.
Previous tenant to us was disabled and eventually got moved out because of the abuse he had suffered from the BF. We moved in and the very first night there was music blaring at 1am until 7am. Great start, not! We ignored it hoping it was a one off.
It wasnt. Cue 2 years of blaring music, arguements and window smashing at various ungodly hours (always quiet during the day) and the smell of the strongest "cannabis" know to man, at least thats what i think it must have been! Even with all our windows and doors shut and rolled towels blocking the bottom of doors we could still smell it strongly. Police were called on a very regular basis, to the point that they said is it **** again when they saw our number come up. It was usually the BF causing the problems, they'd arrest him but within an hour he'd be back out because the doc at the station would say his mental health issues meant he couldnt be kept in. they stopped arresting him for the breach of peace issues in the end and just did their best to move him on back to his own flat.
Council were more than useless, they would not move them because they were afraid of being accused of insensitivity towards those with mental health issues. Forget the fact that we rarely got a single complete nights sleep for 2 whole years.
After about a year and a half I became pregnant, it still took 6 months for the council to offer us somewhere else to live, even with me complaining that I was being forced to inhale the "fumes" from their cannabis and it could well have been damaging my unborn child! One phone call every day for 5 1/2 months to the housing officer, she began to get someone else to take our calls, so we said if she didnt answer our calls herself and sort this major problem out we would be calling once every hour, one day of that and we were offered a house.
New house was only round the corner but much much quieter, we still saw old neighbours from time to time and were told that the issues were continuing as usual. Last year the woman died (dont know what of) and her BF has gone back to his own flat and seems to be quiet now.
If you want to be moved out call the housing officer EVERY day, it may still take months like it did for us but you have a better chance of a move by being a pain in their backsides because they get fed up of the calls and pull out all the stops then.