I did a bad thing and got an Iphone and left T-Moble and the smartphone I got free a year prior, since T-Mobile didn't get service in my new home. I called them to cancel, expecting to get a 200$ termination fee, but when I told them why I was canceling, they waived the fee due to my address not being in their coverage area. all they asked was I send them a copy of a bill that shows my name at that address.
Thanks to this treatment, I'll be moving back to T-mobile when/if they ever get 3g coverage in my area. It seems to me that burning your customers on the way out is a sure way to ensure they NEVER come back.
The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" (I found it!) but "That's funny ..." -- Isaac Asimov