http://www.crtc.gc.ca/eng/INFO_SHT/G3.htm
The CRTC's Fact Sheet for sound levels and the loudness of commercials. According to them:
Ongoing difficulties with audio levels should be reported to the programming service involved, as well to company who delivers the signal to your home. Ask the programming service to check the audio levels being fed to its transmitter, taking care to note the specific date and time of occurrence and the program or commercial involved.