Validity of Agreement of Sale

Period of agreement is only 3 months but you have waited for completion of sale transaction for more than 3 years, therefore you may sever a Notice stating the sale agreement is teminated after expire of 3 months itself and you are not legally bound by the agreement along with the Advance amount paid by the Purchaser by way of D.D. or Money order and wait for the reply.  In case the Purchaser refussed to receive the amount then file a suit for declartion that the agreement of sale is un-enforciable as time barred.

 In your case agreed time  for making the balance payment was 3 months and the purchaser did'nt make balance payment within the time limit and even in 3 years from the date of agreement .Time is essence of contract and therefore purchaser is not entitled to get the flat from you .Before selling the said flat to another issue a legal notice to avoid the controversy and refund him the advance payment .

well said mr.mani