MTN worst customer service ever

So . . . I finally got a hold of them on July 14th and cancelled my contract . . . Or so I thought I paid end of July (probably grace period), then again end of August 2020. I called to enquire, The guy at retentions said that it's a fault on their side and that I would be refunded in 24hours. That never happened. I received another invoice this morning to be paid at the end of Sept 2020. When I called in, they said that it had only been converted to a prepaid on Sept 2. What happened to my cancellation?! And Why am I getting billed?! Then the lady puts me on hold, to check something, and never comes back. After almost 15mins I hang up and called again. With that one, the lady cut me off. I've been trying to get through for over 2 hours. Get a message about "high call volumes". With bad service like this, that's no wonder.