Contract Cancellation!! Useless

Been trying to cancel my father in law's contract for a month now, but the MTN team has been nothing but unhelpful. The excuse is that the Banking App is offline and therefore the payment "doesn't reflect". How long will this go on for? Does he have to keep paying for a contract that no longer exists?? This is unacceptable and the worst service I have ever received. This is daylight *******, to be billing a pensioner who doesn't even have a contract anymore. Exploitation at it's finest.