Citibank Credit Card Complaint

Citibank Credit card department,

Identity theft / Fraud / Embezzlement Texas

So I recently had another complaint with CFPB and it looked like it was resolved. Thought everything was fine. Now the Citi CC company is making responsible once again for fraudulent charges. I got my bill in the mail and they are saying that i spent $840.00 which I thought was resolved. They sent me a bill saying that I used my card back on - which I know is a lie. I just recently got this card when it transferred over from - Costco CC. So my complaint is why am I being held responsible for this???? I thought Citi made it clear to me that these were fraudulent charges .... I wish Costco would of not swicthed me over to this Citi CC. They are the worse CC company that I have ever dealt with. If you own one of these cards, be careful and try not to use it. They will make responsible for charges that you didnt even make.