Canadians planning to book a flight in the next few weeks may want to take advantage of a limited-time offer from Air Canada. The airline announced on Wednesday that it's offering customers seat changes and standard seat selection for free on flights operated by Air Canada, Air Canada Rouge and Air Canada Express. However, the seat selection must be completed on or before Sept. 12. This seat change fee was implemented by the company in January, despite an onslaught of complaints from Canadians when it was initially scheduled to take effect. Only one change is allowed within the validity period of your ticket, and the free change only applies to fare brands that allow ticket changes.