Autopages overcharging on contract (2)

I signed contract for upgrade. Ever since upgrade I have been overcharged. They charge me for new device and now my old device as well. Without my knowledge hereof. When I asked about this after first month they said it was incorrect they will credit me. Never happened. Now after second month they say it is new rule from headoffice and they can not do anything about it. <br> This is my second complain and still waitning for feedback for one month now.