cheating by pvt bank in disbursing loan on wrong property

I had booked a 2 BHK flat in the year 2011 in Delhi/NCR and loan of amounting to Rs.17 lacs had been disbursed to builder from a private bank. Suddenly, builder deserted from market and project was not completed. My EMI is going to bank. One financial company took the possession of above incomplete project against their loan amount under SARFAESI Act. Recently I have visited the project site and saw some confusion then I asked copy of documents of my booked flat from the bank. On going through the paper I am very surprised and shocked that my allotment letter, permission to mortgage of property is for Flat No.A-904-A (1320 Sq Ft) but triprite agreement is A-904(1600 Sq Ft) and my EMI is going for Flat No.A-904. It is not understood how bank has disbursed loan against Flat No.A-904(1600 Sq Ft) whereas Allotment letter is for A-904-A(1320 Sq Ft). Now, I am feeling the confusion between A-904-A and A-904 while signing the paper. What should be done by me.