I have an AMEX horror story - it goes like this.
While a roadwarrior for Platinum Technology I was expected to front all expenses and get reimbursed.
This resulted in a routine rolling balance of about $10k.
Upon my resignation, Platinum decided to be nasty and denied my final expense report as "excessive".
Leaving me without the cash to pay the balance.
So I phone up AMEX immediately to let them know there is a problem and to arrange a payment schedule. We agree on a timetable and I agree not to use the card until payed off.
Every week they call to tell me I'm delinquent, send me threatening letters, and every week I ask if they have a record of the agreement. They do not. I fill in the latest goon on the situation and schedule and they say fine - no problem. Meanwhile I'm paying them as fast as I can. (Platinum came through with the cash about 3 months later).
But they still trashed my credit rating. Multiple derogetories.
So they don't honor their agreements and they screw you if they can.
Fuck em.