I've got a premium economy Aeroplan booking for YYZ - YVR in July and I got an email notifying me that the return flight has been delayed by a half hour and I'm now seated in economy. The annoying thing is that there's a flight at my original flight time, on the original aircraft, with room in premium economy, but I don't see it as an option on the rebooking site. In fact I don't see any premium economy options on the rebooking site, despite there being room on several YVR - YYZ flights that day.

Am I correct in assuming my only real option here is to call Aeroplan and try to get them to rebook me on a flight with premium economy space?