According to the askBA on the question fo "Booking online where departure country is not your country of origin," it states that Amex is not accepted for bookings in South Africa!! This is totally untrued...
I have booked countless trips with my Amex within South Africa.. Anyone else has problems with using Amex? I wonder why this is a restriction?
Will all credit cards be accepted for travel departing from another country?
Provided that you can select the departure country from the menu on the homepage, you will be able to pay with your credit card. However, there are a few exceptions, mostly related to local currency and banking restrictions, and in these circumstances certain cards will not be offered for payment in certain countries. For example, American Express cards cannot be used currently to pay for journeys departing from or within South Africa or Gibraltar.