Originally Posted by
Stranger
Haven't you heard of Star Alliance upgrades, which AC is now participating in?
(Granted that would require the ticket to be booked in B class which sound unlikely.)
Also, can't do a *A upgrade on a codeshare flight. In OP's case, YVR-YUL should be upgradable if booked in Y/B, since it was ticketed under the AC flight number. But YUL-YVR (NZ codeshare flight number) would not be.