I am a Builder. A prospective purchaser wanted to buy a flat in one of my projects. He has paid 50% of the sale consideration as advance, and the time limit for balance payment was 3 months. However, even after 3 years, he is unable to paythe balance amount, and whenever I call him, he would beg that he will arrange funds in a weeks time, and request for extension. Now that the period is more than 3 years lapsed, can I sell the flat to someone else, and pay the advance money received from the 1st agreement holder. Should I serve a notice first and then take up the sale. I do not want to forefeit his advance. I want to pay it back. Please let me know the right course of action .