Refund of amount paid towards Request for Reservation (RFR) Form

Hi, I booked flat in pre Launch,under construction, RERA registered project in MUMBAI. I had ONLY signed RFR form at time of making payment. On asking for receipt of my payment made online directly from my bank account, I was promised that I will be given an acknowledgement of the payment made alongwith a copy of RFR form as early as possible that is within 2 to 3 days. I used to call them frequently and even personally visited the site to discuss regarding my receipt, copy of RFR Form and Further process. There was no follow up and Proactive service at all from sales Team, lots of discrepancies, faults and mistakes in amount.All this factor that too at the start pushed me back and I decided not to go further with the project.I talked to the broker regarding the entire issue and my final and determined decision to cancel booking.It was on the same day that Finally I got a mail and message from crm team regarding payment received and receipt will be sent to you shortly.This was exactly the 7 th day from the booking date.But again a big mistake by them in amount.The next day itself I personally visited site discussing all the acts of sales and crm team, my final decision to cancel and request for refund of amount paid.After that I mailed them several times.In one of the mail,First they apologised for the inconvenience caused and requested me not to go for cancel and to retain my booking which was also done at the time of visiting the site.Later on when they failed to change my mind, they sent me an email stating that there is a clause in RFR Form that is signed by you. The clause is that in case of cancellation, Builder has the right to forfeit the amount. It was in this mail that Finally I got my copy of RFR Form attached.Also they are not ready to give me details of senior person to whom I can discuss my issue. I want to know that can I Claim refund of my amount as RFR Form had the clause mentioned regarding forfeiting and signed by me. Also I have not got any hard copy of the receipt till now. The only proof I have is my bank statement as payment was done online, mail and message sent by them regarding payment received,one mail in which they apologised and the last stating that no refund will be given.Also It is clear that it was the faults, mistakes, extremely poor service and lots of discrepancies from sales team that forced me to go for cancellation. Can I claim refund on the above grounds of reason?Also I have read that as per RERA provision, the clause of forfeiting the amount can be VOID. Does this applies in my case? Where should I complain? How should I get started? How long will it take to get refund? Please guide me as it is my hard earned money.