Builders issue of construction at side walls and backyard.

Dear Sir, I need suggestions on the issue of construction done bybuilders of my society on my flat side walls and backyard area which has blocked air and light of my flat. It has damaged my internal walls and external walls. I own a flat of 1352 Sq Ft Covered area. The builder of the society with some of his other partner is doing construction on my side walls and backyard area is touched to my balcony and bath rooms. My flat is Ground plus two story and the side wall construction that this builder is carrying out is of Ground plus four floors. The builder without my consent is building flats at adj on my side walls. He used my side walls without my consent. Now I have few questions: 1. Can I file case against him in local court 2. I've done loan on this property what are the procedures for filing the case. Do I need to inform bank about the filing of the court case 3. What is the remedy available as I have photocopy of the registry of my flat. 4. What is the fine and punishment for this crime that builder is doing. His construction seems unauthorized and illegal construction as per the local body bylaws. 5. I have already submitted complaint to the MC local body no action has been taken. 6. I had filled application for RTI about the builder approvals by MC but no reply has been recieved till date. Please help me I am being harassed by these builders from last two years now. I also have fear for my life and they've threaten me on my complaints in MC. Grateful to early response please.