Unlock request denied - Reason: Entered IMEI too many times

I am trying to get both phones on our AT&T Account unlocked. 

For one, I was required to pay off the note on the phone, and the unlock request was approved after a few days.

The other is a basic flip phone, which is eligible for unlocking.   When I followed up on the request, it said the unlock request had been denied.  The reason was that the IMEI code had been entered too many times.  (Which is not possible)    Further attempts have produced the same result.  I tried chatting with the computer, but it did not understand.

Please share what steps I need to take to succeed.

Thanks!