Purchased a mortgaged plot

I purchased a piece of land ad-measuring 34 Sq Yd out of a plot No 235 of 200 Sq yd in the year 2004 constructed a shop over it and started renting it.. In the year 2009 I came to know that this entire plot is already mortgaged by the Bank against the credit facilities granted to Mr Riyaz Ahmed first owner of plot in the year 2001. I wrote to the Bank in the year 2009 that this piece of land has been purchased by me and please let me know the status of the loan and securities but bank did not responded. There after I again wrote in the year 2010 at this Bank officials asked me to submit the copy of registered which was tendered by me. I again wrote in the year 2011, 2012 but Bank did not responded. In the year 2013, I came to know that Bank has enhanced the limits of Mr Riyaz Ahmed. first owner of the property and extended the charge over the property besides this also taken a new property. In this connection I met to first owner of the plot and asked the detail than he handed over me two letters. First letter addressed to the Bank intimating the sale of plot no 235 and proceeds of its deposited in the Loan account further offered another plot as security. Second letter was issued by Bank in response of first letter in which Bank assured to consider the acceptance of offered security subject to satisfactory conduct of account. In the year 2015 I asked under noted information under RTI. 1.Provide me the dates on which Inspection of the property was carried out by bank officials and whether they submitted any information regarding change of ownership of property through discreet enquiry. 2.How many times renewal of limit has been carried out by the bank and at the time of renewal whether Non encumbrance report was obtained regarding mortgaged properties from Banks empanelled Lawyer and whether Lawyer has informed change of ownership. 3.When first time Bank came to know that the part of property has been sold out , what action has been taken by the bank. Whether any FIR has been lodged against the borrower for illegal sale and cheating. 4.whether Mr Riyaz Ahmed offered any property as security to substitute the existing security if so , whether it was accepted by the Bank or not. 5.Bank has enhanced the limits from Rs 50.00 lacs to Rs 100.00 lacs in the year 2013. whether enhancement was on the same properties or some additional properties were asked, and at the time of enhancement and noting the extension of charge over entire properties whether Bank was knowing the change of ownership. If yes than how extended the charge knowing the fact that property has illegally been sold out. In response to my this letter Bank responded : Additional Property was taken to safeguard the Banks loan . Plot No 235 on which you have claimed over the 34 Sq Ft remaining part of the plot which is still in possession of Mr Riyaz Ahmed is mortgaged with the bank along with other properties as such No FIR was lodged. I again wrote the Bank that I have purchase 34 Sq yd land and constructed a shop over it and running the business but you have show my share as 34 Sq ft. Bank again replied that “please refer our letter no under RTI in which your claim has erroneously been mentioned as 34 Sq Ft same should be read as 34 Sq Yd. Now I want to sell out the plot for marriage of my daughter but failed as whenever any purchaser visit the Bank , Bank officials says that entire plot is mortgaged whereas I understand that except my part rest remaining part is mortgaged. I request all learned lawyers to advise me how to move forward in to the matter as I do not have any other letter except this information and that too under RTI.