Property Dealer cheating

Last year me and my cousin agreed to sale off our shares through a property dealer. He paid the agreed amount but got us to register as and when he got the buyer for the said plot. We didn't smell any foul play as he was of the same village, but after end of all this, out of curiosity I checked the registration office website and to my horror found out that he got us to sell more than our share in that plot. Now we are trying to talk to him to either pay us rest of the money or talk to our other neighbors to adjust the wrong thus done, however, as you can guess, he is just ignoring any of our requests. Please note we have another plot of a different khata next to that sold plot and we are afraid he might acquire that plot to adjust. Though the registry paper showing correct khata number of only the correctly sold plot. Its almost an year since this happened, can you please tell me what options I have now? If needed I will be happy to provide more specific details about this transaction.