Seller not returning advance

Hello all, Seller agreed for price of property 3.15 crore and we paid 15 Lakhs as advance. He asked us to prepare 2 document one on stamp paper with 3 Cr and not to mention about advance and another plain paper 3.15 and 15 lakhs paid by Net banking. He signed only one document with 3cr which he asked us to use for Bank purpose and did not sign other one. After asking many times in whatsapp he never replied on that topic. Termination clause says if not working we will come as agreed per terms. He only gave sale deed and Khatha documents and plan. Bank asked us additionally Sale and Construction agreement entered between Owner/Developer Assignment agreement document which is mentioned in the Sale deed Adequately stamped (Stamped with 0.1% of the transaction value) agreement to sale executed by Seller and Buyer Tax Paid receipt for year 2022-23(furnished one is of year 2018-19) Encumberance certificate from 01.4.2004 to till date for subject flat Loan got approved subject to providing documents in month but he never came back. He never gave them and said he does not have assignment agreement and rest all he will provide during registration. He as NRI was not fully aware of tax liabilities was working with lawyer to get TDS details. So he kept us saying please wait on hold as my lawyer is working on tax liability. PNB is also asking me to pay more. After 1 month we followed aggressively he came back and said TDS is high as NRI and also PNB housing put him prepayment penalty so he can't give for original agreed price and increased to 3.50 Cr. We said we cannot afford 35 lakhs increase our loan eligibility is less and have to pay for registration additionally and we don't have that much money and want to come out of it asked him to return 15 Lakhs. He is not returning and saying he will return only after he gets prospective buyer. We are already staying as tenant in same apartment and he is asking us to pay rent otherwise put interest and adjust. Asking us to show property to prospective buyer. As tenant also he did not honor we moved and kitchen was not available for 2 months and we had to follow up with modular kitchen guys and get it done. We paid for all the workers upfront as he said he does not have gpay and will reconcile in then rent. He promised wardrobe which he never gave. We paid full rent as we thought as prospective buyer we will do buying fast and do ourselves. Now he is blaming all on us and not returning. Can you advice should we file law suit on him. He is Business man we are salaried people and don't want to loose 15 lakhs + 5 lakhs as rental agremeent advance. We have all the Whatsapp transcripts.