When commission staff refers a customer complaint to a carrier, the carrier must:

(1) Provide its initial response to commission staff within five business days from the date commission staff referred the complaint to the carrier. The carrier's response must include the results of its investigation into the informal complaint and any document related to the move requested by staff. The carrier may request and commission staff may allow, if warranted, an extension to the initial response due date.

(2) Respond to commission staff inquiries requesting additional information or documentation relevant to the informal complaint within five business days.

(3) Keep commission staff currently informed of any progress made in resolving a claim for loss or damages not resolved within the first ninety-day period of the claim by informing staff in writing, for each thirty-day period thereafter, of the reason for failure to resolve the claim.