I looked at one of my recent flights and these are the T & C.
AIR MILES Flight Program Terms & Conditions
A $15 + applicable taxes booking fee was applied on each ticket booked on airmiles.ca.
Cancellations, name changes or refunds are not permitted.
No price increases are permitted once ticketed.
Ticket is non-refundable. Tickets are valid on flights and dates shown on the ticket. If applicable, changes must be requested prior to original departure date and time. Changes may result in a higher fare, increase in Reward Miles, and are also subject to a $60 change booking fee (plus applicable taxes) which is in addition to the Airline change fee of $50.00 to $300.00 CAD. Change fees are applicable per ticket per change and will vary depending on Domestic, Transborder or International Travel, advance change notice and class of service.
Itinerary changes may be subject to restrictions such as advance booking and minimum/maximum stay.