Auction property

We have bought a plot through auction. We have made the payments on time till 25%. We have to make a payment of 75% to the bank in 15 days. We have approached another bank to purchase and construction. As the loan process was taking time we have put in a written request to extend the date as loan processing is taking some time. The bank has granted the request and have given the extension letter. The bank who approved the loan for purchase has given the DD to the bank and a sale certificate was issued to us. As we have bought the property we have started construction. In the mean while the borrower who was defaulted has filed a case in DRT to get his land bank. The court case was going on and in the mean time the we have occupied the property. The DRT has given the judgement that sale is set aside as there are no rules for extending the time and also the bank has not followed some procedures as per the sarfesi act. The judgement was also given asking the bank to repay the amount that I have paid to the bank with 6% interest. The bank who sold the property has counter the appeal against the judgement in the higher court and the case was dismissed in the higher court as well. Now that we have taken purchase and construction loan we will not be satisfied with the refund as we have incurred lots of investment for construction as well. Now it's clear indication that the bank who sold the property is at pure fault for which we are suffering. Please advise how do want me go ahead to recover the amount that I invested in purchase and construction. The time when we bought the land there was no proper development and now the colony has merged with lots of developments. We would be in very bad position and great loss if we just get the purchase amount. Please help us how to counter a case against the bank who sold us as we are not responsible for this loss. We have been going through mental tension and even my father expired due to heart stroke 2 months back which is the main reason of tension. We have lost all our personal and professional life's in this matter. Request your advise on the below. The bank who has sanctioned the laon has done the mortgage on their name and we are not sure how to come out of this caae and gerlt our complete money back from the bank. As a average middle class people coming from society bank doing this type of cheating has incurred a lots of loss to our financial and personal life's. Not sure how to go further.