Mr.Altaf,
As the possession of the property has not been handed over to you, you are just an owner of the prooperty on papers. Excecution of Sale Certificate coupled with handing over the possession of the property makes you the real owner. Breaking open the lock is certainly an offence. But the complaint should be lodged by the Financial Institution. Your remedy can be sought only against the Financial Institution. Please ask for the refund of the amount or vacant possession of the property. If the Financial Institution fails to do so, please approach the appropriate forum for relief. In my opinon, eviction of the borrower from the property will be time consuming.