If a customer needs to report a lost or stolen debit card, Marshall & Ilsley Corporation typically advises that prompt action is essential to protect their finances. The customer should look for the phone number associated with debit card services on their account statement or the official website. Often, there is a dedicated hotline for reporting such incidents, which can facilitate quick card deactivation and prevent unauthorized transactions. It is important to have relevant account information on hand, as this will help verify identity during the reporting process. Additionally, the customer may want to monitor their account statements regularly for any suspicious activity until the matter is resolved. For the most accurate and up-to-date information, users should refer to the current web page associated with Marshall & Ilsley Corporation for further assistance and instructions regarding lost or stolen cards.