If he resigned, not retired, he'd have SRC tickets but no access to TRIPS.
AMEX, are you sure you're using the correct email address? PM me if you have a doubt. I was using an old one and also puzzled at the initial lack of response, but once the emails starting going to the right place they were actually surprisingly helpful even with multiple changes and re-listings.
Kind of funny that the two most efficient departments in EK seem to be the one dealing with people resigning and another one dealing with people who've resigned...
Oh, and you can also email them your credit card information as a payment option, as they suggested. I would suggest, um, no. hahah! Any local EK desk can process the payment.