Costco's transition from American Express to Visa is drawing complaints from customers.
On Monday, Costco ended its 17-year exclusive partnership with American Express.
Social media is filled with customer complaints.
Many say their new Costco-branded Citigroup Visas have not arrived. Others report problems activating or using their cards or accessing their accounts.
Costco has not commented.
Citigroup says it's received 1.5 million complaints.