Impact Meters is penalising me for their mistake

After moving into the townhouse on 20 November 2021 and paying my electricity and water account every month, I got the shock of my life when Impact told me end of September that they had switched my water account with the one on the unit upstairs and as a result I owed Impact R11 900.00. I enquired with the lady upstairs and she confirmed she had been complaining about the huge water bills long before I moved in. My normal water consumption at the previous residence was around 12-14 units per month. This bill from Impact shows consumption of up to 50 units per month. I suspected we had a leak somewhere in the system. Two leak detectors came and confirmed there is no leak. The only logical explanation is that there is a fault on this water meter. Credit control asked me to escalate my complaint to their GM a guy by the name Tony, I received such an arrogant response from him. My electricity was cut on Monday, I have never met such bullying from a corporate, this issue I am taking it to the authorities.