What is the breakdown of your charges? If it is for data, and you use Netflix, be aware that Netflix plays a dirty little trick with their service. By default your netflix account profile is set to Auto for quality. That means the signal quality from Netflix will be set automatically based on your internet service speed. The higher your speed the higher the quality they will send, and of course the higher the data use. You can go into your account in Netflix and set the quality manually to limit your data accumulation.