Neighbours from hell

A rather complicated problem here. My boyfriends (adams) parents have been living in their house for over 20 years, and there is now a serious problem with the new neighbours. They have been complaining about the amount of noise Adams parents are making. Now these people are in their mid 60's and they do not make a peep of noise. Now the evil neighbours house has no carpets, due to the previous owner removing them. So, any noise Adams parents make sounds must sound so much louder than it actually is. They have complained about the garden gate, the television, front door, back door and talking during the night, where they are apparently keeping their children awake. The main issue is that the evil neighbours have a special needs child, so if Adams parents complain at all, the neighbours would win every time as they would just use the child as an excuse to anything. Another thing is that the evil neighbours are getting money from the council, however, the dads father owns the house. So the doll money is paying off the fathers mortgage, of which sounds illegal but i'm unsure. Now, myself and my boyfriend needed to live back at his parents house but his dad is too scared of us making any noise that would cause trouble. So we are having to live at my grandparents. Plus, because the evil neighbours have complained about the television making too much noise, (it is not loud whatsoever) they have now resorted to getting a seperate speaker to play the tv sound on the other side of the room. This situation is apaulling, but adams parents cant do anything and wont do anything. I can see them live like this for another 30 odd years. They wont move beacuase its been their home for over 20 years. They shouldn't have to. I'm thinking about trying to organize a meeting with a police officer or the council to get some advice, but i dont really know what to do. HELP!!!!