According to the Chase customer service page, the department handling member services can be reached by calling 1-800-432-3117. Contact numbers are also found on Chase bills sent to customers and on the rear of Chase credit cards.
Chase customer service is available 24 hours a day, seven days a week. In addition to calling, Chase can be contacted by secure email through its website once a member has logged in or via Twitter at the address @ChaseSupport. Chase can also be contacted through the mail. The mailing address for general correspondence is Card Services, P.O. Box 15298, Wilmington, DE, 19850.