Is this an AC thing, a "from the US" thing, or 6th freedom thing that could happen with any carrier and geo?
As we all know, scheduling and routing is not guaranteed. Do the EU regs even protect against this (going the other way across an ocean?).
There should be better recourse to cover the marketed offer (and "one stop in Toronto and the SSL" was the offer here, even if via a friendly FF).
Is the AC denial to change the ocean hop based on some long established industry rule?