Missing OC and CC of the building in BMC

Hello, We have booked one flat , it is 35 years old building. We sold our flat and transferred money to the owner of flat. Though we knew the flat papers were not readable properly it was little blurr ,we still purchased the flat beacause it was terrace flat which was very attractive. Now the payment is already half done and while filing for loan the bank asked for OC and CC which is not available with the owner so we checked in the society and BMC as well and it seems the building does not have OC and has partial CC . So we cancelled the deal because we dont want to take such a risk because the amount is not less if something happens in future we will be in loss. Now we have cancelled the deal and informed the owner beacause of this we cannot proceed further, he is not cordinatinv and postponing the date of payment. Till date he has returned only 1%of the payment dons by us. Its been two and half months we follow up regularly he says dont worry niether he signs on any document aknowledging the payment has beeb done by us. We have bank records with us which is proof that we have given the money to him. Now we have no money and we also sold our flat to someone . We are facing lot of issues regarding this owner . He is not cordinating and threaten us that if we follow up everytime then he will not cordinate with us. Please advise what needs to be done.