Airtime purchased on my credit card (Not by me)

I noticed that Airtime was being purchased on my Credit Card. The number was a prepaid MTN number that had once belonged to me but since I had not used it in several months the number was recycled. <br> <br> I then phoned FNB to find out how this number was purchasing airtime on my credit card (A card that I diddnt even own at the time that I had this old number). It took me two hours being transferred between departments and each time I had to do a full verification. My patience ran out after inserting my ID number and card number for the 20th time.<br> <br> The response from FNB was that even though I had changed my cell number on their system, my old number was still on the system and therefore without any pin or verification the number could dial 140 and purchase airtime on my account. The number was not linked to the one card I had back then then but to my whole account which includes all my new cards too. <br> <br> I felt like this is a huge security breach considering a complete stranger had access to my new credit card but the ***** department said they could do nothing because it is airtime being purchased. I was very disappointed by FNB's response and lost faith in their security measures.