My son is on a prepaid monthly plan with no data. He just uses the wifi at home and public areas. His phone was acting up so he reset it and didn't realize the data was turned on again and his phone downloaded updates before he realized and now we have a $20 data bill because it used our wifi. I don't understand if we're prepaid to have no data why his phone lets him use the data and I'm not very happy about this. Any suggestions?