Originally Posted by
Definitas
The BAPP terms state clearly and without ambiguity that the card holder and companion will travel in the same cabin. Not may travel, not could travel, not will travel unless BA decides Otherwise, not subject to BA overselling your fare category, et al.
Are you actually suggesting suing Amex when someone on a 2 for 1 voucher gets upgraded to a higher cabin and not the companion?
Fully agree with others that Amex is entirely unconcerned by the issue and that the OP should focus on BA. If you buy a ticket on Expedia for BA flights, you arrive at the airport, BA agrees that your ticket is perfectly valid but tell you they don't have a seat for you, you'll sue BA, not Expedia.