CarSafe Tried to sell warranty car insurance Saint Louis, Missouri

I received by mail material stating that the warranty on my buick had expired and I should call the number on the card to receive information on extending by protection. After nearly accepting the offer that was given, and giving my credit card number, I decided not to go through with accepting the offer until talking with my wife. I told them I would call them back if we decided to accept the offer. I received a phone call within minutes trying to get me to accept but I refused and told them I would call them back. I have not agreed to purchase the insurance, but am worried that they have my credit card number.