Customer service article: "How do I pay my Bloomingdale's Credit Card bill or Bloomingdale's American Express® Card to your bloomingdales.com account. If you don't want to take these steps online, you can also call American Express customer service using the number on the back of your. For Serve® American Express® Prepaid Debit Accounts, you must have activated Customer Service, but you cannot stop bill payments sent electronically.