Contract cancellation

I've been trying to cancel a cell c contract since November 2020. After my 24 months contract ended I was told to call cancellations dept and I did but I still get debited on my account. I don't know how many times I've called to cancel but still no luck and if I ask for a reference number they say I'm going to get an SMS but I never get it. Instead I always get calls to do an upgrade and when I tell them about the cancellation, they say they can see on the system that I've called. It's been 12 months now and someone needs to do something about this. And I want my money back, all of it, because I'm not even using that contract cell number. I don't see a reason to call the call centre anymore cos it's just a waste of my time. Someone please contact me to resolve this cos I'm tired of calling you. And my money must be credited into my account immediately.