thinks their granddaughter got her debit card information and opened a Venmo account
How does this not do anything but meet the definition of an "unauthorized electronic funds transfer" in 1005.11(a).
Your customer made a claim that met all the conditions of 1005.11(b). Now you must investigate following the requirements of 1005.11(c) which includes provisional credit. You cannot require that the customer try to resolve with the merchant before starting your investigation.
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