Inconsistent water billing

I bought property at De Deur Augast 2018. By January 2019 i was already owing manicipality more than R10000. So i made an arranngement to pay off debt over months. I then had to use borehole water and cut off manicipality water completely. To my surprise the bills still couldnt go down. November 2019 i had a bill of R16000. I went to complain and it was cut to R1100 without explainations. Which i paid. That was 16th of December. On the 19th of Dec i received another bill of R2900. Now im confused and angry i dont really know what action i should take. There were months where i had huge bills from estimated figures where actual meter readings were not done. Complaining at the local manicipality doesnt help. I feel im ****** in daylight. The More i try to catch up on payments the more i am taken advantage of. How can bills be higher when im using borehole water than when i was using manicipality water????