MTN owes me money and ignores my requests for help

I’ve transferred my contract from my fathers’s name to my name a month ago. It was confirmed that the august bill would be paid from My father’s account, and from end september my account would be debited. One 1sep (for august bill) they have debited him nearly double what the original contract price is, with no explanation as to why or how they came to that total. At the same time, they tried to bill me for more than the contract price. Again, no explanation. This results in them greylisting my number (and affecting my credit record) which is out of my control, because there is no way of resolving this as they keep closing tickets before anything gets resolved. And I have no way of contacting them. Worst customer experience I’ve ever had. It’s a joke, who gave these people rights to work with customers. Stay far away and go to literally any other network provider.