Sale agreement

Sir i have made an registered agreement on 24 Apr 2014 after paying 24 thousand stamp duty to purchase a land costing Rs. 11.66 lakhs. As an token money i paid land owner Rs. 01 lakh and took time for lumsum 6 months time to pay the balance amount. But no where i have mention the auto cancelled agreement. After agreement two time i have made payment of 1.5 lakh and again 1.5 lakh (means total 4 Lakhs) i paid him. six month finish on 24 of November. when i gone with the remaining whole balance money, he is telling time of six months has crossed. Now i have to think about price. i have sent a notice to u. But i have not received any notice from his side till now. After that i also sent two notice to him. But he is not interested in meeting or talking to me. After that i was having some personnel problem so neither i nor he contacted each other. Now he is not ready to sell to me. He is selling it to some one else. I and some more person they tried to convey him but he is having greed in his mind. Now i want to know or want to have advise from u. 1. Can he sale his property to anyone else. 2. Can he increase the price of property more than what he mentioned in agreement paper. 3. what the best i can do to purchase this land. if he play game.. 4. What is the validity of this registered agreement. 5. Please advise me how to proceed further. 6. I am giving an application to Registrar/Tehsildar/SDM requesting to stop any registration against this property. 7. I am also filiing a civil suit for stay. Kindly advise me what the best.