I had a situation 10 years ago with Amex. I was out of town for three months. I had my assistant paying my bills for me while I was gone. She neglected my Amex bill.
When I returned home, amongst the late notices, was a cancellation letter. This letter advised me that unless payment was received by X date, (a Sunday) my account would be cancelled.
I immediatly phoned customer service, explained what had happened and offered to drive to the Ft. Lauderdale office and pay the bill, (a Saturday.)
I was told that this would not be necessary and to overnight the check to them immediatly and then call with the tracking number. Of course I went right to FedEx, called Amex with the tracking number and was assured everything would be fine.
My card was cancelled on Monday two hours after they signed for my FedEx package. Nobody cared about the notes in the file regarding my conversation with them about this.
I have survived without an Amex card for 10 years and see no reason to go back.
TW