Developer reluctant to refund the advanced money after bank has refused my Home-loan request.

I entered into an ‘Agreement for Sale’ deed on the 1st of May, 2024 handing over a cheque approximately of Rs.250000.00 to the developer in order to book an under-construction-flat (not registered under RERA) on the outskirts of Kolkata. The local branch of SBI that I rested reliance on (for reasons of financing), refused my Home-Loan request with observations raised by two of their empaneled advocates: (i) 3 Decimals of land area are recorded in the name of Relief & Land & Land Revenue Department as ‘Allotee’ – Please clarify/Present landowners’ status still remains that of an ‘Allotee’ in the records of B.L & L.R.O which should have been rectified as ‘Rayat’ (ii) Only 6 decimals (equivalent to 3.8 Cottah(s)) of land found recorded in the names of present owners; why then sanction plan is given over 5 Cottahs of land (iii) Affivavit of Legal Heirs or Certificate of Legal Heirs has not yet been provided even after the file has been returned twice already asking for the same. I met the developer requesting him to submit documents according as the bank demand, but he refused and insisted on me taking a Home-Loan from else-where which I strongly disapproved of. In the month of November, I typed a letter addressed to the concerned Enterprise with the developer at its helm & whatsapped it (his email addresses not being available) repeating for refund of the booking amount, within minutes he phoned me & gave expression to his reluctance threatening me with a legal action levelled against me for harassing him or the like. On the 26th of December, 2024 as I talked to him over the phone, he sounded disappointing and replied to pay the money back only after the flat has been sold. As per the ‘Agreement for sale’ deed ‘the developer shall be at liberty to transfer the said property to new purchaser(s) in case of failure by the present purchaser to pay money within the stipulated period of time. The present purchaser’s advanced money shall be refunded after deducting 20% of the consideration money without interest after the date of such induction of the new purchaser is made.’ What should I do now to get that money back? – Pls.