Land developers, nagpur

Dear Sir, I would like to know about Land Developer in Nagpur, Maharashtra. They are selling plot on agriculture land. And agri land is from village. I booked this plot and paid all installments. But still they are not processing registry from Land Registrar Office. They telling land is not NA and it is in process. but now 4 years are over after payment complete installments. Could you please suggest any option or action on it. Thanks Pramod