promissory note

I have purchased a semi furnished flat from a reseller in which the builder has registered the flat in my name. I have paid all the sale consideration 3 years back(taken housing loan). As the apartment is semi furnished it was agreed that balance of 3 lakhs has to be paid after the completion of construction at the time of taking keys from the builder. For which 2 promissory notes were executed (2 lakhs + 1 lakh) along with cheques as security only. Till today the construction is incomplete. The reseller has taken the cheques & promissory notes. Now the re seller has files a money recovery suit claiming that i have borrowed money from him 3 lakhs + interest + court chrgs. He wants attachment over my property. I have not borrowed any money from him. I have not enjoyed my property. I am paying rent every month. I am paying bank EMI every month. Please advice me what should I do. The re seller has not deposited cheques in court as the cheque dates are more the 2 years old. He has deposited only promissory notes. Please advice how should I prove the truth,