I can't find an e-mail address for Amex. They sent me an offer of 10K MR points to enroll my Business Platinum card in the Pay Over Time feature. Always, when I go to the registration page, it tells me that they can't process my request at this time, and I should try again in 48 hours. I've been trying for a couple of months, have phoned Amex twice to no avail, and now need to secure message them with a copy of the offer, which expires on November 1. But what electronic address can I use?

Thanks.....