How to recover Money given to someone?

My father and I were in search of a Flat from Jan'21 onwards.. Through two brokers we came across 1 flat..The flat was a 1320 sqft flat.. The owner demanded 43 lakhs for the flat and the deal was settled on 42.5 lakhs But he had two conditions 1. On paper the flat cost will be Rs. 52.5 lakh as per his original costing 2. We will have to give 10 lakhs advance which he will return at the time of signing the registry papers for the flat. The person seemed like a gentleman and hence me and my father fell in his trap and transferred Rs. 12.5 lakhs online as we decided he would return 10 lakhs and we would take a 40 lakhs loan from bank whose formality we completed with ICICI BANK. Though the registration was to be done in 15 days however the person kept stalling it giving excuses. After 3-4 months we decided not to own the flat as he was not keeping his commitment of giving back Rs 10 lakhs at the time of registration and alao his wife die of cancer, hence vastu dosh of the flat..He wanted us to move in the flat and sign registry afterwards.. It looked wrong and hence we demanded to return our money.He is still stalling us and not giving the money We have 3 proofs 1. Online transfer of money 2. Call records 3. What's app message What to do in this situation?? How to recover money legally and in short period of time??