Is the amount received from the insurance company permissible, and what should be done after discovering that the insurance was not free as the bank had stated, and is paying the insurance premium unintentionally considered a harm that requires a specific course of action?

It is not permissible to voluntarily enter into commercial insurance. However, if one falls into it unintentionally, we hope there will be no accountability for it. For it is authentically reported in the Hadith (definition) that Allah said: "I have done so," when the verse descended: "Our Lord, do not impose blame upon us if we have forgotten or erred." [Al-Baqarah: 286]. You are not required to give any amount in charity unless you do so voluntarily, because what is given in charity is that which exceeds the principal. The amount is lawful for you as long as you are unable to terminate the insurance contract. You must seek forgiveness and repent.