Citibank Credit Card Complaint

Citibank Credit card department,

Privacy Texas

I have had an - - card for years used as a membership card for Costco. Costco switched to Citibank for their membership. Citibank opened an unsolicited credit card in my name and sent it to me. The instructions said to activate it to authorize it. I chose not to activate it. A month lateer I got a bill from Citibank for the renewal of Costco. ' In order to settle with Citibank, first they asked to verify my personal information. After that, they said they could not cancel the card. I would have to go to Costco, and that I owed Citibank for the fee. I finally annoyed Citibank through - and they decided they could cancel the card after all and reverse the charges. I want to know who gave them the personal info, Social Security, DOB etc. I never authorized this to Citibank. I want to know what actions I can take against Citibank and whomever gave them my information. I tried to resolve this through Costco, but they never responded.