Builder is not refunding the full booking Amount

Hello, Respected Legal Practitioners, I confirmed with a person from the builder's office (let's assume Mr. X) who was dealing with me, that if I cancelled the booking before the agreement, I would be paid the complete amount without any cancellation charges (I have recorded the conversation with me), so I went ahead in good faith and I had booked a flat by paying the booking amount of Rs. 1 Lac online using IMPS. The next day, when he came with the booking form, he quickly filled up the details after I signed the document and left with the booking slip and sent me the pictures of the same afterwards using whatsapp. I then noticed that there is a clause that says if I cancel the booking, they will deduct Rs.25,000 and return the balance of Rs.75,000. I reached out to the same person (Mr.X) and he again confirmed over the phone that the clause is there but the complete booking amount is refunded in the event of a cancellation before agreement. After that, I asked for all the relevant legal documentation from their side (atleast the soft copies) so that I could perform a legal search on them, but they didn't provide me with the same after repeated calls (for 6 continuous days). So I decided to visit the complex and talk to the already residing families over there, and to my surprise, they informed me that even after 12 years of residency, they are unable to mutation because of the completion/occupancy certificate unavailability. So I again asked them to provide me with the complete document set as I wouldn't be signing the agreement before checking their authenticity. But they said that we can only provide you with documents after you pay us 20% (although it was written in the draft agreement that the purchaser would verify the legal documents). My suspicion grew stronger and I asked for a written note on a company pad with an official stamp that if my loan from SBI is not processed after paying 20% due to legal issues at the builder's end, they will return all the money and not deduct anything and I will go and apply for the SBI loan by myself and not through any third party consultancy decided by the builder. Mr. X's boss denied both the requests and literally abused and threatened me that he would not return the full booking amount but deduct Rs.25000 as written on the booking slip and also try to delay the payment of the balance money as long as possible. (60 days was written in the agreement and 45 days in the booking slip if the builder cancels it)  Then I searched more about them and found they do have a history of torturing innocent people who have canceled their bookings, and some people have not gotten their money back even after 2 years. I would like to know how I should proceed in this case. I do have all the call recordings of the conversations between myself, Mr. X, and Mr.X's boss. Thanks in advance.