The ONLY thing in Reg E §205.11 that hinges on a written statement of a consumer's claim is provisional credit. If an oral claim identifies the customer, the account, the transaction(s) and the reasons the customer thinks there's an error, you've got to, within the time constraints imposed by §205.11, investigate the claim and finalize your decision; and, if the customer's claim is valid, adjust the customer's account subject to any limitations in §205.6.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8