I can bet a 100 bucks it was a sales person who was bored at the shop and going through customer lists and checking bills and accounts to see if they could save you money by adding a feature and they accidentally clicked your data package off
I used to do this when I worked for cingular out in Lancaster and I made a shit ton of commissions off of it by just noticing a simple add on feature and calling that person and explaining that they could be paying 5 bucks a month for texting instead of paying per use and costing them 25 bucks a month