Delay in refund of booking amount

Dear Sir /Madam, I was planning to purchase a flat in delhi. I visited one flat and found satisfactory. I was asked to pay 12lac so that agreement to sale can be prepared and rest 35 lac loan can be availed. Since agreement to sale is prerequisite for home loan, I paid 12 lacs through RTGS to the builder. During technical evaluation of bank, it was found that it did not follow DDA guidelines and does not have requisite approval so my loan was rejected. I asked the builder to cancel my booking and refund me the advance amount. In agreement to sale, it is mentioned that either of them right to cancel and full refund will be made. Then builder paid me 5 lacs after a month and asked one more month for rest 7 lacs amount. Now it is more than 7 month and still he is giving me date and delaying. After I insisted a lot, recently he paid 1 lac. He is still holding 6 lac. Pl tell how can I get my hard earned money back. I had taken personal loan to pay him advance or token amount. I am incurring interest and he is delaying every time.The problem is that builder is in New Delhi and I live at Bihar so can't go to Delhi everytime.