Need to complain directly to the airline? Click here
Need to file a formal complaint with The Aviation Consumer Protection Division? Click here. (NOTE: International airlines may or may not fall under this agency's jurisdiction. If your flight originates or ends in the U.S., you may have some rights enjoyed by customers of U.S.-based domestic airlines. However, if your flight does not involve a U.S. leg, then, no, don't file a complaint here.)
Complaints about Air Canada (Google Search)
If anyone knows of an official governmental agency for filing a formal complaint against this airline, please email the webmaster.