I think Joe is asking if you can require that the request for documentation after a claim is denied be in writing. There is nothing in Reg E 1005.11(d)(1) that says this is a permissable practice, and considering a claim of error can be made orally, I don't see how you can require that a request for documentation be in writing. Adding extra hoops to the Reg E dispute process (like filing police reports) is asking for a UDAAP citation.
As for what you provide...was obtaining a sales receipt with your customer's signature what you used to base your claim? If so provide that. If you used previous statement showing the customer routinely makes purchases at the same location, then use that. If it is a picture of the customer making the withdrawal or purchase, use that...etc....
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