I'd go to Eng, since that's your faculty. They might say they can't do anything since it's Comm, but Comm might send you back saying you're in Eng they can't do anything for you.
I was registered in Soc Sci and had to get permission for a Hummers course and when I went to Humanities, they told me I had to go to Soc Sci. I went to Soc Sci and they said I had to go to Humanities. I refused to go and one of the receptionists in Soc Sci called Hummers and got it all straightened out.
So, yeah, go to Eng first and maybe talk directly to an academic advisor.
http://www.eng.mcmaster.ca/current/advising.html