Over-Debited and No network

I have a contract with Mtn which I opened in 2021 December, took an uncapped WiFi rooter from them for R500. Beside their garbage network, they’re now over debiting me, tried to call them and ask them what’s the problem and why am I being debited extra money the lady said I must give her my details and I did , the she said she couldn’t confirm my information and I must go to an mtn store, I called and begged her to try again and she profusely refused with attitude. Can’t wait for this nonsense contract to end so that we can can go out separate ways.I’ve also been complaining about their network since I got the rooter and they haven’t done anything to fix it while they take my money every month