I have had an iphone for two years now...I put data restriction on all the lines (only wifi can be used)....and I DIDNT have to pay the 30$ data plan fee....all of a sudden today I received a message from at&t "did you know a data plan is required for your iphone? for whatever reason, our records indicate your iphone did not have the correct data plan. we have added the appropriate data plan."

what can I do to get around this???