I was supposed to fly BOM-LHR-YYZ, but AI was massively delayed (6 hours+) They were actually telling people to go to LHR and "see what happens" once you get there, which would have been too late to catch any AC flights.

Only after an argument, they agreed to put us on BOM-DEL-JFK-YYZ - 12 hours later - but still arriving before any of the LHR options, where everyone would inevitable get stuck overnight.