Builder put lock out of my house

I had purchased a new flat in resale from X who had purchased the said flat 8 years back from builder and was staying there since 5 years. After my final sale deed X has vaccated the premises and handed over the keys to me. I visited the property after few days and apart from my lock there is additional lock put from outside by someone and a notice which says "do not open the door without permission of builder" I was shocked and on enquiry the security said builder has put the lock. Builder's manager said I have to pay rs. 10lakhs which is balance of Mr.X with builder to clear the issue. There is no balance of Mr.X with the builder and he was staying there since last 5 years and had not received any communication for the same. The builder has not completed the OC nor completed the society formation process yet and is demanding anything for NOC for registration of flat so we decided to do registration without builder NOC which is allowed as per my knowledge. Now builder has put the lock outside just below my lock and is threatening that the flat will never be mine again. Why am I to suffer after paying all the money to Mr.X and my EMI has started. I cant afford to pay rent and EMI at the same time (EMI is not on the said flat but on my mother's flat as she helped me with money by taking loan on her own flat but I have to pay EMI). Mr. X has shown me all the receipts as per the purchase agreement between him and builder but builder's lawyer says there is no final sale deed between Mr.X and builder so the property is still builders and Mr. X was never the legal owner of the flat.