When I spoke to Air Canada reservations to cancel the reservation, I was told that the funds would be credited back to my credit card. Upon checking on the Air Canada website, I found that this reservation hadn't been refunded because the agent on the phone had not actually processed the cancellation. The credit card company then wanted a cancellation number to prove that I had canceled the reservation, but the airline never gave me such a number, so I had nothing to provide. If you'd canceled your flight online, then Air Canada would have sent you a written confirmation with a cancellation number and the other particulars. Air Canada, like other airlines, records its customer service calls for "quality assurance" purposes, and can review the transcript.