Mark,
Your contract is first with the airline that issued your ticket, and second with the airline shown on the ticket regardless of the operating airline.
In other words the issuing carrier's Conditions of Carriage apply to things such as ticket issuance, refunds, etc. while the ticketed carrier's CoC apply to things such as missed connections, baggage allowance and liability, etc.
The operating carrier, if different from the ticketed carrier, has a contract with the the ticketed carrier not with the passenger.
Edited to add:
IATA Resolutions are no longer binding - most members apply the provisions but this is at their discretion.
Don't forget that the contracting airline has an obligation to fulfil its core part of the contract. Getting you from your origin to your destination. Although not stated in writing (as the AUC observes) this has always been held up by the courts, and that includes covering reasonable expenses you might incur.
IATA fares are not cheap. In fact they are embarrassingly expensive. The two airlines could have a joint fare at a more reasonable level, but I doubt you would find this on-line.
And sadly the AUC is no longer in business. The powers that be in the UK decided that a small group of industry experts were too old fashioned and have transferred their responsibilities to a bunch of mandarins who know nothing about the business, but who are dedicated to protecting passenger rights, whatever that is.
Last edited by ExXB; 8th Jun 2012 at 09:30.
Reason: Add some additional comments