Land developers, nagpur

Dear Sir, I bought Plot from a Land Developer from Nagpur Maharashtra. And I paid 60% of agreed amount on installment basis. during 2007 to 2009. But after some time the owner of this firm died in road accident and all property transferred to his brother. But his brother closed all setup and transfer his office to some other location. they did not inform us. I wrote a letter to this firm for demand to get registered property on my name with payment of all dues OR return the amount which I paid in 2012. I have acknowledgement of it. But he never replied on it and he is not coming to me in his office. only 1 or two time I talk with him through his employee's mobile from his office. I have agree to pay all dues with other charges, but still he is not giving any attention to me. Please suggest what is the option to get registered this plot on my name or the action I can take. I have a agreement copy and receipts of payment. Please suggest. Thanks Pramod