Mental & Physical Harassment at the hands of the Neighbours

It has been 3 years since we shifted to a new independent floor. The neighbours above us are unruly, rude, abusive, and have raised their hands on us over disputes that can easily be sorted out via verbal chat. They are sadists who love poke & prod and pick up fights and greet us with abuses. It is just not one family member but the entire family. They spit paan on our cars, purposely make their dog pee on our cars, and always park wrongly so we face trouble. The lady in the family purposely throws dirty water from her backyard and does not repair the holes in their sheet and all the water comes draining down on our freshly washed clothes. They have trained their drivers and maids also in various that always causes us trouble. We live in a non-cooperative & gated society, so it is difficult to raise our concerns with any organized body. We are a set of very simple, educated people who have always refrained from doing anything wrong. But these monstrous neighbours are testing our patience every day and we are running out of options. Please help us with the legal options and the legal acts on the basis of which they can persecuted.