What to do builder had physically assaulted my family

I, am currently a graduate student. I live in a building. The builder live in the same building as of mine and he had illegally constructed two floor in the building. My father decided to complain to municipality, he wrote a letter and took the sign of all the building members. After knowing this the builder his two sons and his wife beaten, me and my family in which, I and my mother get injured. We have medical slip from a gov hospital. The police suggested us not to file and FIR however a General Diary had been lodged. The local councilor and municipality are seemed to be also involved. And i think he will continue to do construction after bribing the officials. What can i do? I have less bothered about the building, I am willing to teach them lesson as they will not dare to physically assault anyone. We have video evidence against them. N.B: The builder is a Muslim, and I am a non-Muslim and We live in a Muslim dominant area.