I just happened upon this decision issued yesterday:
https://www.otc-cta.gc.ca/eng/ruling/290-c-a-2014
In summary, the claims of 5 travelers against IB for cancelling TATL segments have been dismissed for lack of a valid contract. The CTA decided it had jurisdiction for the complaints even when the flights concerned were BA codeshares from London to the US because the journey ultimately ended in Canada (see [15] and [16] of the decision).
Better news for the complainant who filed against CZ for a downgrade. It continues because:
[49] The Agency has reviewed China Southern’s international tariff on file with the Agency, and notes that the tariff did not include provisions allowing China Southern to downgrade service or provide a refund based on erroneously quoted fares. On the other hand, the Agency notes that the refund was not provided and the ticket is still “open for use”.
[50] In light of the above, the Agency is of the preliminary opinion that China Southern has contravened subsection 110(4) of the ATR in applying terms and conditions that do not appear in its tariff.
CZ has until 11 August to file its response to the CTA.