Looking at the article it seems the airline refunded the first ticket. Not the most expensive one. Why not refund the more expensive ticket she was forced to purchase. The airline made the mistake and should have flown her at the original fare. What happened to her was a de-facto fare increase, if this was allowed what' s stopping any airline from cancelling tickets and then extorting more money from passengers if they want to fly that day. It did not cost Air Canada any more money to fly her on the same plane. I would sue Air Canada and the employee who made the decision to cancel the ticket to get back the difference.