Illegal parking construction's in apartment

Dear Sir I am staying in apartment there are 6 flats in our apartment 3 ,2 bhk flat & 3 ,1 bhk flat on each floor 1 bhk &1, 2bhk flats our builder has build 2 illegal rooms on parking are & combined with 1bhk flat stated as duplex to landowner later on land owners has sold his 1 bhk to one of the 2 bhk holder in our apartment.... Now 1bhk holder showing his power s to other society members that 2 illegal room in his custody whenever we ask for keys to those 2 rooms he came to all apartment holder with daily clushes ...given a thread to us if we demolish his parking 2 rooms I will also give complaint to demolish total apartment because there is some planed change work done by builder in our flats also We have given complaint to Nagpur imroovment trust to demolish the illegal rooms of parking & they have demolished also Right 1bhk flat owner who having these rooms under him sending notice by lawyers that you could not teaching tuition & etc kindly guide us how to tackle situations