Water Department is overbilling me

As the title says, the water department is overbilling me for the past four months after I moved into my new house. They somehow billed me based on an estimated reading, which was way beyond my actual usage. I had an appointment with the meter technician and he verified the correct reading last month, but today I saw the estimated reading again for this month… In addition IT TAKES FOREVER for the billing department to get the refund credit to me. When I called they said it will take 30-60 days to process.

How the hell can it be so difficult to get the money being overcharged by the water department? Has any of yall experienced this before and could give me any advice? I even complained to my district council but it doesn't seem to expedite the process.