Refund of flat booking amount

I was booked the flat in Mhalunge Pune Maharastra in oct 2014, and paid 7 lakhs as a booking amount by check payment. i have receipts and bank account statement of that transaction. after that there was no any construction activity so i given a flat booking cancellation mail to builder in sept 2015 and asked my booking amount back builder was not taken any action on that mail so i again gave him reminder mail in oct 2015 but he not responded and not taken any action. I was continuously followed him for refund by making phone calls his staff always promised new date for refund but never refund my amount. Then in may 2018 i got one mail form builder mentioning that he is transferring the project to another builder and he register project in RERA as a on going project and he want a consent from me to do so. then i called the builder and ask for my amount then he told me that he will not going to refund my amount back. so i was given complaint to police station against builder i got reply from police that they can not take my FIR as its civil court case and not a criminal case. So please give me legal advice in this case.