I just wrote an actual letter, like, on paper. Been a long time since I've done that.
Trying to dispute a bill with Telus and emails fall on deaf ears.  Maybe a certified letter is going to get their attention. I'm not even sure how to make it certified, I guess I can go to the post office for that.  Certified letter that mentions the word "attorney" and "legal action" a few times will hopefully get them to drop it. 
Long story short their alarm system kept glitching out, I cancelled it because of that, but they keep sending me a bill for a false alarm and their phone and email support has been useless.   
I'll probably end up being stuck paying it in the end...  but at least I can't say I didn't try.