So only 24 hours late... not that bad. :-) But seriously, I have seen worse.

Just heard today from a colleague. His son and family (three kids and wife) were supposed to fly YYZ-YYC yesterday (maybe same flight?) but flight was cancelled. Rebooked to today. When more or less ready to board someone got sick and they rushed to emergncy. Missed the flight and likely will end up cancelling the whole trip.

Then there was our daughter in law flying from BOS to Regina last summer with two kids. Flight BOS-YYZ canelled, rebooked the next day on Delta to YVE. Ended up spending a night in Vancouver, ultimately two days late...

But coming back to your story, clearly the agent you talked to made a mistake when unchecking you. This said, you should not have called, just gone to the airport. One does not lose a seat assignment by letting checking in to when at the airport.

The seat fees, they should reimburse. But on the positive side, think of all the penalties they'll have to pay by virtue of being late. Either under the EU rules (but do these apply to Switzerland?) or the Canadian ones... :-)