It is very simple to address both complaints and compliments to AC customer service.
Simply go to this link and complete the form.
I have had quite prompt response on most occasions (though I have not always got what I wanted.)

http://help-aircanada.com/aircanada-...ue.do?lang=ENU

The auto response often "promises" a very un-optimistic response time, but I have never waited that long. It is even faster on Twitter, but the length of a tweet limits what you can cover.