Ilegal construction of Pent House on the Teerace

Dear sir, I am from Hyderabad,Prgathinagar,JNTU Kukatpally. I am the individual owner of flat in a Apartment ,The land which was used for Construction of Apartment is totally 400 sq yards. As per AG PA between land owner and Builder and as per plan total 12 flats are build on the land as Cellar +4 means Cellar, Ground floor, First floor, Second floor and Third floor Each floor 3 flats which are Equal in size as 830 sft and the builder registered a un divided share as 33 sq yards to each flats means 396 total and out of 400sq yards. 4 sq yards not registered to any body. One small room he constructed under the Water tank room initially like as store room for apartment. Recently that builder extended taht room like as single bed room falt seccretly with our notice. Since from last ten years that builder fellow is gaining rental income by giving on rent around 3000 rupees per month. it is not in a notice of majority flat owners, he is doing all this matters with the support of the president of our apartment. Now we raised this issue with builder from majority of owners objection like its ilegal you need to demolish or vacate like that. He answered he is having right as he not registred left over 4sq yards out of 400 sq yards so now he is trying to sell and registre that unofficial single bed room pent house to some body. is it legally possible to stop that selling of unauthorised room .