Afrihost refusing to cancel my month-to-month contract

I was struggling a LOT with my internet connection since Oct 2018. I was in constant communication with Afrihost trying to resolve the issue. Nothing helped. When I finally called early December to cancel my contract they finally came out with the truth that the specific package I was on was giving so much trouble that they don't even offer it anymore - something EVERY person I spoke to at Afrihost failed to mention. They then asked me to please give them another chance, they would send me a replacement sim immediately and give me a free month to decide whether I still want to cancel. Two days later I still had no internet, and I started looking for another service provider. By the time the courier company finally called to arrange delivery, another service provider had already made major home installations and I had fantastic internet connection. So I told the courier company that I won't even be taking the sim, since even the service when trying to persuade you not to leave is terrible and slow. I contacted Afrihost to cancel any and all contracts. I did this multiple times with absolutely no success. They keep telling me that they don't know whether the courier company actually returned the unused sim yet and they can't cancel anything 'till then. That makes absolutely NO sense. Their arrangements with their courier service provider etc has nothing to do with me and whether I want to continue using their services or not. So this month, still no cancellation, same excuses and despite the fact that they are not even my service provider anymore they are still debiting money from my account and stating that they can't do anything about it 'till feedback has been received from the warehouse. I am completely at my wits end! After struggling for weeks on end I have now reached a point where I will have to start taking legal recourse because no company has the right to debit money from my account when I have notified them multiple times to cancel my account and I am no longer using their services.