Tried booking the following itinerary, and the agent came up $100 more than what was on ITA:

London (YXU) to Vancouver (YVR) - Fri, Jul 26

Air Canada London (YXU) to Toronto (YYZ) - Fri, Jul 26
Air Canada 7708 Dep: 11:45AM Arr: 12:26PM 0h 41m De Havilland Dash-8 Economy (L)
OPERATED BY AIR CANADA EXPRESS - JAZZ Layover in YYZ 3h 34m

Air Canada Toronto (YYZ) to Calgary (YYC) - Fri, Jul 26
Air Canada 125 Dep: 4:00PM Arr: 6:17PM 4h 17m Airbus A319 Economy (L)
Layover in YYC 1h 13m

Air Canada Calgary (YYC) to Edmonton (YEG) - Fri, Jul 26
Air Canada 8225 Dep: 7:30PM Arr: 8:20PM 0h 50m De Havilland Dash-8 Economy (L)
OPERATED BY AIR CANADA EXPRESS - JAZZ Layover in YEG 1h 55m

Air Canada Edmonton (YEG) to Vancouver (YVR) - Fri, Jul 26
Air Canada 255 Dep: 10:15PM Arr: 10:51PM 1h 36m Airbus A320 Economy (L)

Cost per passenger (including taxes & fees) CA$421.63
Total cost for 1 passenger CA$421.63

He mentioned AC does not have an L class (which was visible on ITA and shows on Aeroplan a booking into flex) so why does it show on ITA?

He tried to claim that only S class was available.