Refund of Money

In the month of Feb’21 me and my husband we paid 5lkh Rs to a local builder as he was constructing a building by demolishing some Chawls around. As the offer was good of getting a 1bhk flat for 25lkh at Andher we thought it is a good offer and will go for it. Builder showed us all the documents related to the said construction and said as the land belongs to airport BMC permission is not required and Airport NOC will do. After paying him 5lkh Rs we tried to apply loan but all the Bank refused to give us loan saying the agreement is not a registered copy but a notary copy. Knowing the deal is forge we canceled our booking. For which he said the money will be refunded within a month and now it is almost 4months no update from him. He gave us cheque of 5lkh which got bounced twice And now he is threatening us saying if you do a case on ke in consumer court I will declare myself bankrupt and will not pay your amount The problem is only proof we have of payment is transaction details not any receipt Please suggest what can we do