Land Dispute issue

After booking the flat and almost 1 yr later builder informed about the land dispute issue. Due to land dispute builder is not able to get retaining boundary or driveway passage is also part of disputed land. For 6 months there was only meeting happened with no progress as per builder. meanwhile we have been started with interior and took possession as already there was a delay of 6 months. Now when we took procession and started staying with family then builder informed that land dispute is not resolved. current Land owner should resolve the disputed property hence we are in helpless situation. With all this disputed land Builder is not providing any details however he claims issue will be resolved but same time we see the land encroached has been covered with fencing done. Now since there are 45 land owner to the property with builder who blame current land owner being the culprit for land dispute. We being only 20 person who booked the flat hence not sure how to proceed and fight for the piece of land. Please suggest.