Consumer Redressal

I had booked a flat with Amrapali Noida exten and deposited 8.30 lac but bank has refuse the loan and i had cancel the flat after 7 month, and has refund my booking amount only not interest, when i demand the interest amount they have refuse , how can i get my interest amount of my 8.30 lac for seven month. when i was fail to one month late of next dune amount builder has notice me he will cancel the flat of charge the interest , but builder has refund my booking amount after cancellation of two month. so kindly help me , can it get my interest amount from the builder ?? hope an early response from your end. regards Fartiyal