MTN calls unanswered

I have been trying to cancel my sharelink data contract with MTN since it's expiry in February of 2021. They tell you it can only be cancelled telephonically and then they never answer the phone. Furher to this I have upgraded my cell phone contract over the phone 3 times and it never reflects. End of the month the same old contract still applies. That has been ongoing issue since July last year. I was just on hold again for 46 minutes trying to cancel the sharelink. This company clearly just send the cancellation calls to an unmanned phone.