HELP!! unwanted noise transmission-Acoustics Forum-Acoustic Fields Forum

Hi guys and girls, im kev.
This may well be the totally wrong place to be asking, but im wondering if anyone can help….. my inlaws have a semi detetached house, their neighbour has had some building work carried out and in the process installed a series of steels which replaaced the downstairs walls to create an open plan. the problem is that one of the steels has been built into the party wall ( which may turn out to be illegaly done ) and now there is huge noise transmission into my inlaws house. They have put up with it for a while but its now become a real problem as new people have rented the place and make a lot of noise. The inlaws have repeated asked them to be more considerate and explained the situation but every time the neighbours go out, their dogs bark and howl non stop. Im trying to convince my inlaws to go to the building regs people / council but they are reluctant. If they wont do it, what can we do to the wall to dampen the noise? i can get access to the end of the steel in the cavity as we know roughly where it is.
Thank you for any response and sorry if this is the wrong place to ask.
Kev