Refund of amount for the property purchased due to a govt borewell present inside property

I have purchased a property from IDBI BANK LTD under sarfaesi act. On the same day when bank took physical possession it was handed over to me giving me a handover as well as sale certificate at the site. After that I came to know that a govt borewell and encroachment of CNT as well as govt land is also there inside the campus. After two days of my possession the first borrower repossessed the property back by putting a lock and said me that he was not informed by Bank about physical possession so he does not accept such act of possession and my possession is illegal and if I will again trespass into the property he has all rights to physically harm me. I have informed bank but they are asking me to file an fir against the person. The local police is rejecting the plea stating that the title is not under my name as I have been just issued a sale certificate so I should contact bank first. I have also asked for refund from bank stating all the issues but bank is saying that for refund I have to file an FIR against the person and then only they can initiate refund. I have already raised a complaint in writing to bank but they are not replying. What could be done in this case?