Builder has mortgaged my flat after doing Agreement to Sale registration with me

Dear Legal Councils, * I have purchased a flat from Builder in Pune On 28th February 2013. * An Agreement for the same was registered on 5th March 2013 at Sub registrar’s office. * Before Agreement, i have paid 1796800/- to builder for which i have receipts issued by Builders office having revenue stamp on it. * The Builder, Borrowed a loan of Rs. 8.5 Cr. From Financial Instituion-1 which was sanctioned on 20th March 2013 and the mortgage deed of the same was registered on 25th March 2013. * Remaining amount against total sale consideration of 30 LACS were paid in April [deleted]/- and in May 2013. via Home Loan Amount of 2530000/- from LICHFL (Although we were not aware of this mortgage to Financial Instituion-1 by builder, builder has deposited this amount in Escrow bank account which we came to know in 2016). * After full payment, Builder has given us possession on 28th May 2013. * We have found the notice affixed under 13(2) SERFAESI act at our society’s office sent by Financial Instituion-1 to Builder for outstanding demand of 1.58 cr. in 2016 and builders account was declared as NPA. * Builder was absconding. So we did police complaint against builder and Financial Instituion-1, but Police did not register FIR. * We contacted Financial Instituion-1 authorised officer and sent him documents, agreement to sale, payment receipts, possession letter issued by builder and index II, via email. * On 6-9-2016 Financial Instituion-1 has issued a release letter saying that they release the charge on the flat and will not have any charge on this flat in future. * Now in feb-2024, Financial Instituion-2 affixed notice on society gate saying that they were earlier known as Financial Instituion-1 and Builder has not paid the amount and under 13(4) they are taking possession. * since my flat is included in the list of properties mentioned in Schedule 1(A) which lists all properties offered as secured assets at the time of disbursement, we have sent the notice to Financial Instituion-2 mentioning sequence of event and furnished them the copies of index II and Release letter by Financial Instituion-1. * Financial Instituion-2 responded that they have taken symbolic possession and they are in process of application for SERFAESI 14. they further said in the reply that, it was my duty to do the due diligence before entering to this transaction. But I have done due diligence before entering into agreement to sale and haven't found anything in Feb 2013. What steps we should take?