I have a query pertaining to a land dispute

Purchasedland area released from Ceiling 4500Sq. Mtr out of total13300 Sq. Mtr.year 1985. survey was measured by Deputy Collector & Competent Authority, Urban Agglomeration Thane in the year 1985 and the entire area of 4500 Sq. Meter is marked as “R – ZONE” Further the area had been plotted into 12 equal parts (375 sq. Meter each).Deed of conveyance reg. in 1985,received Index II . The ULC issued the transfer area on each plot owners name vide there order in the year 1987. Received Saath Bara on our name with Pher phar. Some plotsdeveloped some are still vacant.On request of builder Lands Records (city survey office) conducted survey and shows that out of 4500sq.mtrs of land some parts are in other survey number and rest other part in different survey number.(Boundary dispute).givenobjection to the survey in written.Now the builder wants to acquire the vacant plots. Stating that asper city survey it’s their land and that the survey done by ULC in 1985 not authenticate.