Charge more on account.

I just received my January account and with shock I discovered that I need to pay for excesive usage. This is my son's phone. He hardly phone from the phone and is most of the time on WI-FI at home and we regularely check his ballances to make sure he does not go out of data on his phone.<br> <br> I need an explanation as to why I need to pay this high amound. And please provide proof for what you are saying as words does not proof anything. I refuse to pay that amount antil black and white proof are given.