May I suggest contacting them in this order:
phone calls
Faxes
Phone calls are much, much more effective than anything else. One phone call is worth 20 faxes or at least 100 e-mails.
Add in change your voter registration to independant first thing Monday morning. Take your old registration card and deliver it to your local GOP rep and tell him/her “Never again”
Although I've contacted pols mostly by e-mail, I suspect you're right about this. I wonder what your exact reasoning is, though - do you think phone calls have more of a visceral impact?