Is it permissible to continue dealing with an Islamic bank branch that is affiliated with a usurious bank, even though it has a Sharia board, but with observations regarding the extent of its commitment to Sharia principles? What is the ruling on administrative fees deducted from the client, and are they deducted from the principal amount or from the profits in the event that dealing is impermissible? What is your opinion on Faysal Bank and Abu Dhabi Islamic Bank?

It is permissible to deal with an investment branch if it adheres to the provisions of Sharia (definition) and all its investment channels are separate from the interest-based bank. The mistakes of employees do not make dealing with it unlawful, but the Sharia Supervisory Board must monitor this. The way to know the extent of the branch's adherence to Sharia controls is by asking trustworthy scholars in your country. There is no objection to benefiting from past profits that you earned out of ignorance or by following a fatwa (definition), for Allah Almighty says: "So whoever receives an admonition from his Lord and desists, he may have what has already passed, and his affair is up to Allah." However, if it becomes clear that the branch does not adhere, then you must withdraw your money from it and search for another Islamic bank. Faisal Islamic Bank and Abu Dhabi Islamic Bank are Islamic banks and have a Sharia supervisory board, but the reference for judging them is to ask trustworthy scholars.