Private home water bill from R300 to R8000

Our water account averages around R300.00 per month. In March this year we received a bill of R8000.00. Lewis Mngoma from the Joburg revenue department insists that this was to get our water consumption up to date because of \non-availability of readings at the time of invoicing". Our daily consumption went from about .700 KL per month to 6.000 KL for a period of 2 months. I have sent numerous emails to the department and always end up receiving correspondence from Lewis Mngoma who insists that there is nothing wrong with the account and that I need to pay the full outstanding amount. My husband has taken water readings and worked out that we would have had to fill our pool seven time in two months. All I want is for the department to reconcile the account and understand that it is impossible for a normal household to have used to much water. There was a pipe burst just up the street at the same time. But they refuse to accept that that could have been a contributing factor in the astronomical water bill. How do I get them to fix this account?"""