Does AT$t credit cards use citibank

[JThompson24]

got something in the mail talking about how my credit card rates have changed. its my moms credit card she gave me to use. It doesnt say att on it, it says citibank but the account numbers last 4 digits are the same. Does she have another credit card and could it possibly end the same way. id hate to call her and she says to suspend it and give it back.