City of johannesburg not reading meters correctly

They do not read meters. We were give a bill for wate for 15000. Our usage per month is low less than 20kl. I use bathwater to flush toilets i do not even wash my car. Despite numerous visits to walk in centres to log faults sending photos of meter every month via e mail the do not rectify the problem now they have cut our water supply demanding payment for water we have not used. They do estimations of usage and have made a mistake in the process