Under MyBookings on aircanada.com I see two flights for Mar. 19:
AC6826 Tango Plus M
LX146* Tango Plus H
I called Air Canada, but LX146 had not cleared. On
http://www.flightstats.com I get H/9
Interestingly, the booking code changed from M to H. Fortunately, H is available for the upgrade. I'll call again tomorrow.