Fraud by a seller and lacunae of bank

We bought a property which was already mortgaged with a bank (we didnt know that time). Sale deed of the property is with bank only. Seller had cheated on us by saying that original sale deed is lost and he will get a certified copy from sub-registrar. As bank had not registered the mortgaged property with sub-registrar, seller was able to get the certified copy of sale deed. Now we have the sale deed and mutation both in our name. Bank sent a notice under sections 13(2) and 13(4) of SARFAESI act to the seller and put the property on their site for e-auction. Also bank had not registered this security interest with CERSAI which is a mandatory requirement after 2011.  There were only two ways(checking with sub-registrar and CERSAI) to check if the land was mortgaged or not.We did checked both. Please tell if bank if eligible to enforce sarfaesi act when he failed to register the property with CERSAI. There are many more lacunae of banks that then loan manager had done in processing loan. We had filed a crminal case in district court against the seller but case was disposed (dont know on what basis, certainly the judge had taken bribe). We have approached to high cout allahabad. It is very much clear that a mortgaged property cant be sold so the seller is guilty. 13(2) notice under sarfaesi act was given to us as well as to the seller. We had replied to that under section 13(3) of same act but bank didnt respond to us. 13(4) was sent to seller only. Why bank is bypassing all these things. Loan amount is around 30 lakhs. Please help.