If I recall there was quite a discussion on this when the new "simplified" fares to the UK were introduced. I'm sure AC is legally covered as somewhere it will say "subject to the rules on the cert" or something like that. I'd agree though that it is far from clear in terms of customer communication. Why they can't have 1-set of "simplified fare names / rules" to all destinations baffles me.

Sorry to hear things didn't work out. Do you have the option to "buy-up" to an eligible fare class (H - I believe)?