If you live in an area with really shitty coverage and you call them three times to complain and it is documented on your file; you can contact their "customer service" group to let you off the hook. A buddy of mine did this and they let him and his whole family out of a three year deal because they could not justify having better coverage in his area. Bell apparently had great coverage. It didn't cost him a thing.
If you are getting out because of the cost of your monthly bill, I suggest you call Customer Service and do exactly the following:
I am very unhappy with paying so much for my bill. Would you please try to help me?
I know other people are getting excellent deals from Rogers. Quote "Howard Forums" and say you would like to speak to "Retentions".
howardforums.com is a great resource for this info. I don't think you have to join up but can go to the Rogers forum and view the "Rententions" thread.
Repeat the same thing for "Retentions".
Do not get argumentative, speak in a calm voice and ask them for help reducing your bill.
I am a heavy user both voice and data. My bill used to be $225/mo. I did exactly as above and now its $85.
3000 anytime minutes, 6 GB Data, unlimited Texts, enhanced Voicemail, unlimited after 6 PM minutes. So many extras that I would never use them all but at least I am paying a hell of a lot less. I now need two full batteries per day to come close to using it all

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