Neighbour unwilling to stop nuisance and encroachment of common areas.

I would like to know if there are by-laws that govern a builder flat. My Ground floor neighbour is very rude, and does not respond to any plea for home maintenance or management of any type. The family has a policy of non cooperation and mock us with patronising comments and dismissive non-reactions when and if we ask for anything to be addressed to contributed towards. They have placed a 2 ton air-conditioner under our first floor slab over the driveway, that is 15 years old and very very loud. This ac leaks water all over the Driveway as well. We have been requesting its re-postioning to a lower level on their floor or its replacement with a split type unit where noise and leakage can be less. We cannot sleep and have constant headaches due to this background noise that is pervasive and constant. This neighbour has also placed a huge old and loud diesel generator on our roof that shakes the whole building that they are unwilling to remove despite not having taken permission from anyone here. There are several more such issues but we are stuck and dont know where to go with this, as they mock our efforts for dialogue and flatly refuse to take any action. Any provocation results in a "karlo jo karna hai phir". We are sad and need help as we are very unhappy to fight with any neighbours. What are our rights ? Is there any point in trying to approach the law or is the law just another route to harassment ?