If I return my iPhone within the 14 day return period, and I already activated it, would I still be stuck with the extra $20 a month I added to my at&t plan, or would that get canceled as well?
The data plan is listed as "IPHONE DATA + ###" (### representing the number of texts you get) on my bill, so I would assume that if you call AT&T and tell them that your are no longer using the iPhone you could get this knocked off.
Shouldn't be a problem since it sounds like you were already an AT&T customer (and I would guess AT&T might be happy somewhat since they don't have to give Apple part of your fees anymore )
You can call AT&T and tell them that you have returned your iPhone and dont want the unlimmited edge plan which came with it and I am sure they will just strike it off.