(m) Credit transaction means every aspect of an applicant's dealings with a creditor regarding an application for credit or an existing extension of credit (including, but not limited to, information requirements; investigation procedures; standards of creditworthiness; terms of credit; furnishing of credit information; revocation, alteration, or termination of credit; and collection procedures).
What about that doesn't include billing errors? If you are processes errors faster to white people or denying claims because the customer is black for existing account, I definitely think there would be a Reg B violation. I do think billing errors fall under the investigation procedures, but even if you don't, the language clearly states every aspect, and the list is not exhaustive.
Whether you need to do any FL analysis on billing errors is a business decision, but I certainly think Reg B applies to them.