I get that calls can be disconnected; but it seems to happen a lot more frequently with Air Canada. And given it's normally in the middle of a sentence, I think it's hardware not people at fault here.

I do wonder if they said "It will be here tomorrow" or "It will probably be here tomorrow", subtle but different. If they said it will be here tomorrow, they are at fault because they should know better than to promise that.

In terms of the OPs question of what to do next, I'd suggest first calling generic Air Canada who are less unhelpful than the baggage people; and failing that social media "Air Canada lost my bag 9 weeks ago and are now ignoring me" will probably get some sort of "Please PM me your details"?