Booking amount is not refunding by builder after home loan rejected

I have booked a flat in NoidaExtension in july-2019 for which ,50K of amount has been paid by me as booking amount. After builder had started to process my home loan(80% of total cost) from GIC and in end of Aug-2019 , they assured me that your home loan is near to approved & asked me to deposit remainning 20% down payment(around 5L) which I paid through internet banking .GIC also collected some blank cheque and 10K amount(processing fees and other charges) along with my personal docs from me. Now in sept-2019 ,Builder's staff told me that your loan is not approved which caused me to ask them to refund my amount back .In start of Oct-2019 , builder's staffs told me that they would refund whole amount in 3 months i.e. end of december 2019. After passing more than 3 months , their staff had given me 3 post dated cheques from different bank account whereas I had deposited in another bank account given by builder in jan with great difficulties for 3 different subsequent months. Now first cheque has bounced with insufficient funds.There was no agreement signed b/w me & builder