How to recover mortgaged property papers from bank legally now?

My father has taken education loan for my foreign studies in 2008 from branch in where he worked as asstt manager. This was returned to bank with interest in 2010. During this period (2008), my father was dismissed from bank due to bank fraud in his branch. His name was not in any FIR. The title deeds of house I live in were mortgaged for education loan. They have not been returned. I was coborrower of loan with father. The title deeds mortgaged is in my mothers name. Title deeds file (which is with bank) has a printed page on its top which says that due to bank fraud, title deed should not be given to my father. We went to the bank but they said that they cannot release title deeds and we should ask this in writing. We fear that bank may usurp our house as if we initiate return of title deeds. I want to get title deeds back with NOC. I am confused should I give this in writing? Can bank claim our house for fraud today or tomorrow? What are options for recovering title deeds from bank?