Refund for cancellation

Hi. I recently booked a flat 28th April 2016 a society that was almost 80% complete. I filled the provisional booking form. We agreed with 30% payment in 10 months (5% in every two months) and rest 70% on possession.first demand letter was issued in june but they had one line item that was due on 30th May. Then the demand letter said 70% on near completion not on possession. This was not mentioned while booking. They were also insisting me to make 20% payment then only they would give in writing the date of possession. I discussed this with the builder and due to disagreement, I decided to cancel booking on June 18th. We have not entered into bba. Now it has been 4+ months they are not responding properly..initially they said refund Will be processed in oct 1st week now saying in current financial scenario refunds are difficult. I've paid 3.1 lac please advise. On provisional booking form, they have not mentioned the cancellation policy. Though they have mentioned 20% ernest money. What can I do now