CITY OF JOHANNESBURG MUCIPAL ACCOUNT

I have been contacting COJ regarding my municipal account with no success, in November 2022, COJ installed a prepaid meter in my house, my account was paid up in full, but they have been charging me R4000 as from December 2022 till to date for an electricity bill, now they claim that I Owe them R 18 000, how can they charge me a bill of R 4000 for electricity because I have prepaid account, what makes me more angry, I have been querying this since January 2023, they are not responding, now they are threatening to cut off my electricity. I have been flying from Durban to JHB to resolve this issue with no success. i have been carrying cost to resolve their mistake, but they don't bother to resolve it. My Tenants are now scared that they might stay in the dark place because of incompetency at City of Johannesburg.