Dishonest billing and total *******

I was paid in advance to the amount off R 265.86 on this account. Then I paid in another R 316.21. It was noted on the account that I am in advance to the amount off R 582.07. Then Tshwane bills me R 1 112.27. When I phoned the person on the line told me it was based on an estimate. To me this is dishonest billing and if the same is done to other paying customers, Tshwane can most probably ***** millions from unsuspecting customers. Something has to be done about this, because this type of behavior runs South Africa to the ground.