Actually, it is American Express.  I initially had the same suspicions as you, and when I first called the number for American Express that is on the back of my card, they said it wasn't one of their numbers.  But the calls continued, so I called them again and asked if they could contact the number to see if it was legitimate.  They were able to confirm that it was one of the phone numbers for their Account Services department.  They were able to confirm also that I was not the person they were looking for and they even put notes to that effect all over the computer.  Unfortunately, the calls have continued - and this morning they even had the nerve to call my cell phone! It's absolutely maddening!  If I wasn't a customer, I might be able to sue them for annoying me like this.  Still, I'm documenting every call, and if it comes down to it, I will sue them for the times they have made me late for work with this nonsense, putting my job in jeopardy.  I've had it with these jerks!