Iphone tethering to ipad problem with att!?

Ive been using my iphone plan on my iphone 4 as a wifi hotspot using "mywi" so ican connect my ipad to it, today igot a text that att r going to change my plan bcus they caught me doing that, so i called them and i cried for them a little bit and they returned it to the unlimited plan. Is there any way that they wont find out? Cus i need it really bad!!