One of the most obvious examples is Air Canada. I also want to point out that, in Air Canada's case, the use of the courts didn't have the desired effect. The Supreme Court of Canada upheld the Federal Court of Appeal's decision to set aside the damages awarded by the Federal Court to Mr. Thibodeau for the violation of his language rights on one of his flights. Air Canada has trouble fulfilling its official languages obligations.
I should point out that I've never had any trouble getting service in the official language of my choice from the other carriers. I'm thinking in particular of VIA Rail trains, on which I often travel all year round.