Seriously......seriously.. This is a loophole that PAYG people abused. I 100% agree that the unlimited data people abused should be cut off.. this was meant for cheap handsets that rarely see the light of day to a full internet.
popping that PAYG sim card into the iPhone and then using the "full" internet is abuse and needed to be closed.
Pay ATT for what you're using and stop complaining! Or get rid of the iPhone and put the sim card back into the cheap handset that you bought at 7/11 or Wal-Mart.