Property construction delay and fraud

Bought villa property from a builder. Agreement signed about 8+ years back. Within 2 years builder was supposed to handover. Builder took long time to do construction, giving various reasons. Completed about 95 percent now. But did not register the property in our name. We have released the money (Self funded via checks) as and when they made progress. 1cr+ has been released. We are willing to do Registration and take handover as is with some 5 percent still remaining. But itseems Builder pledged our property (along with some more villa) with a bank, after selling it to us and did not pay the mortgage there. They never informed us about pledging our villa. Now the Bank is trying to get their money back by auctioning. They already put one set of villas for auction in the newspaper few months back. Our villa could be coming up for auction anytime soon. Builder has told they cannot register our villa in our name until things are settled with the bank and said they will clear that out very soon. But now it has become very difficult to reach the Builder. They don't answer phone, even if we go to their office the right people do not meet. Given that it is 8+ years old agreement, value of 1cr+, What options we have now? Is there someway we can safeguard our property still so that it doesn't go to auction? What action we can take on Builder either to speed up Registration of our property or get money back?