Unexplained Additional Money on municipal rates

My rates are increasing in one month. I have paid money but even after paying the money increases. I cannot keep up and i really don't understand why is it the case. September i called and i was told that i am owing +-R3250 but now on 02 October am told that i am owing +-R4100. On top of that i am supposed to pay R180 on a monthly basis but my maths is not adding up. I am tired of calling and getting the same thing which i do not understand . Maybe i will get a better explanation on the public platform. Its exhausting to pay money n u don't see any difference.