I got a text message from AT&T saying that I'm continuing to enjoy my tethering and need a valid $45 tethering plan to do this. Problem is, I never used tethering and don't even know how to use it. They're going to "update" my unlimited data plan to the 4 gb one which costs more. I even checked my data usage and I'm using less than 1 gb each month. How do I get them to stop changing my plan? Thanks in advance.