I need some guidance on a customer who wishes to have his bookkeeper and his office manager be able to contact our bank and retrieve both Business and Personal Account information. He does not want to put them on the account as a "Convenience Signer". How should we handle this request? Are we in compliance if we simply obtain something in writing from the customer? Any suggestions?

I would require a business resolution documenting the individual has been given access by the appropriate governing authority (board for corporation, etc.) to have full and total access to all account information.

We require a letter from the business owner stating who may have access to what information and we require a PIN number for each party.

Whether a letter will suffice depends entirely on the type of business entity. A letter from the president of the corporation will not protect your bank at all if he hasn't been granted such authority by the Board of Directors, but it will work fine for a sole proprietor.