Banks must exercise extraordinary diligence

Dear PAO,

After the death of our father, our mother contracted a loan with a financial company secured by our parcel of land. Aside from the real estate mortgage, she also executed a Special Power of Attorney (SPA) which authorized the creditor to lease, mortgage or sell the collateral. Following the full payment of her loan, she demanded the return of the land title. Unfortunately, the creditor informed us that it could not return the land title because it was mortgaged to a bank. On the other hand, the bank told us that it has the right to take possession of the land title, since it is a mortgagee acting in good faith. In the SPA, the name of our father appeared, but it was physically impossible for him to personally sign the SPA because he had already died prior to its supposed execution. Is the bank a mortgagee in good faith?