Unauthorized Construction and harassment

Sir: I have purchased a ground floor flat from the landlord on verifying the GHMC residential building approval (for G+2) in the year 2007. The builder has been constructed unauthorized flats against the plan and no proper parking is allotted. As per the landlord, the old borewell inside my registered flat area between two rooms kept on a temporary basis, and the builder will assign a new borewell in the parking /common area. since then one of the builder who is residing at the third floor has been informed on the new borewell. he has developed personal grudge and influenced other flat members and trying to attack and harassing us since then. it is almost 14 years , we are allowing borewell due to which our house walls are getting damaged/cracked. Since no contribution from others, we born the expenditure thrice for its repair. we have strictly told them to assign the borewell outside. they have started entering in to my premises and lodged a complaint at GHMC stating that I have occupied common area. I have approached court on the same. Please advice how to take action against Mr. Naveen ,Builder who is the perpetrator here. Meena