Global Water billing change overcharge maricopa, Arizona

I recently receive my bill for oct. 2010 from global water when I was shocked to find it was over $100 for one month. Assuming it might just be a mistake I paid it planning to follow up. I then received my bill for nov. 2010 again it was almost $100. I went to the global water website and pulled up a report of water usage over the last 8 months. The report shows an average water usage of 6000 - 7000 gallons a month up until oct. and then it jumped to almost 13000 gallons a month. Shocked since its just me living in a very small home I called Global water customer service to report the problem. I was told that my water meter was recently replaced and that my previous meter had not been giving proper readings so these were back charges for all the usage I didnt pay for previously. First bull there is absolutely no way I use more than 7000 gallons a month by myself, second if what they say is true which I doubt, why am I paying hundreds of dollars in back charges for their faulty equipment. This company has been a rip-off from the start their charges are way too high and they only get away with it because we dont have another company to go with. My average water bill when I lived in chandler AZ about 30 miles away was never over $30 my lowest bill since I bought my house in Maricopa has been over $60 and usually higher. This company needs some competition. Has anyone else had this billing issue?