Sorry, I'm not a consequentialist. And if harm is your criterion, what harm is done to anyone by calling customer service to cancel your account instead of lying so you can do it via email?
I'd like to think that I could do something productive with that time that would make my life or the world slightly better. Plus the frustration of sitting on hold would negatively impact my health and state of mind.
That seems like quite a lot of harm; certainly not worth an empty idealistic gesture that would not help anyone.
Being put on hold does far more damage than lying in this particular case.
Not that they are a great source for morality anyway, but if you're going to use them, at least use them properly, mom.