To report a lost or stolen Wells Fargo debit card, you can either call the bank's customer service at 1-800-869-3557 or log in to your online banking account and navigate to "Services" then select "Report Lost or Stolen Card." Customers can also report a lost or stolen debit card through the Wells Fargo mobile app. When you call customer service, have your account information handy, including your account number, social security number, and other relevant details to help identify you and process the request.