JHB Water ill treats pensioners

Can someone please let me know how JHB Water tells pensioners to pay 46k when they were incorrectly billed by them. My poor parents quede there for the whole day (as old as they are) trying to explain to a gentleman by the name of Brian that they have opened numerous calls for the past 5 months with no luck. Brian was very rude and didnt want to hear them out, they cannot speak english as fluent as he can, but why ill treat customers who drove all the way with their pension money to resolve mistakes you cannot fix. Please can we have a reachable contact number here, they are threatening to cut my parents water supply for something not even theirs. I pay for their water monthly with all receipts as back up, can someone please help.