Service desk
You can always explain first to the Costco desk where they show a various amount of card replacements buts tell them that you lost it and you need a copy
It depends. If your Citi credit card is your Costco membership card, you'll have to contact them. Otherwise, customer service at Costco.
Customer service
Customer service desk gives replacemet
Just go to customer service and they will give you a new one.
Tell the door guard that you lost your card and to allow you to go to membership area and get a new one
Membership will issue a new one.
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