If AT&T is still sending you bills after you left them, you need to contact them to see why you are getting a bill after you ported out.
I have the same problem when I did the switch to Tmobile in the store may I say.
i was told it would be a smooth transaction and that for doing the switch they would pay off one of my phones (device).
i said good, please make sure i have nothing outstanding wilth at&t . now I still see it in my monthly bill/
I'm.Not a happy camper as pf a recent letter i received from collections saying i OWE $945.00 for a device that was never paid for from AT&T.
Why is Tmobile doing this to people who come to them and why can't i get this resolved with some straight forward answers????