Billing Problem

I have received my bill today and this is totally wrong. I have been overcharged and left in debt. My bill was recalculated from the date i joined. I have done some quick calculations on my electricity alone and i have used approximately £320 of electricity since joining and i am being charged £1170 instead. I have done the calculations deducting my first meter reading from today’s reading x unit rate plus standing charge x 152 days. What is going on???