Credit One Bank Suspicious Activity By Bank Las Vegas Nevada

I have had this credit one bank card for a while and I usually have low available balance. I decided to pay the card off and since Ive had a high available balance, I get fraudulent charges on my account. After the first time I called, they turned one card off and sent me a new card. Within one week, I had more charges on the new card that I have never used. Something is not right with this. How could a new card that I never used be compromised in less than a week? All the charges were made in other states.mostly the same area in California and three in Brooklyn, New York. I live in Georgia. They claim its going to take up to 3 months to investigate. I dont understand why they approved the charges in the first place because it was obvious that it was suspicious activity.