I think you should put a cap on over-usages on phones so parents can't get surprised with enormous bills they can't pay. Example, data usage is only 200 MB. Once a person goes over that limit by more than it costs to pay for the next plan that would cover the over-age, then charge the customer for the correct plan that month and not hundreds of dollars for the overage use. Bump their plan to the next plan and put an extra 5 or 10 dollar fee onto it for administration fee to do that. But then the next month, they are back to their original plan fee unless they go over again. And it this happens for more than 4 or more months in a row, tell them to switch to the higher plan or they will get a penalty fee added.