Makro Credit Card ****

Today I received an sms (14h24) that a purchase of R13900 was made on my Makro Credit Card at Makro Woodmead the store that I usually visit. How is this possible as I have my card on me? How did they know I had this amout of credit on my account available? Is this an internal job perhaps? They usually need your ID when you purcjase on this card, has my details been leaked somewhere? I called to block the card, but there is someone jeopardizing your customer info! I want to know what is going on here!