MTN Bad Service.

My number has been suspended due to non payment. But I've been trying for the past week to get my card details changed as the card they have has expired. What do I do to fix this. One bounces from pillar to post in the call centre. Either its not their department or they are off-line or they dont have access to that system. And you stay on hold for 15 minutes at a time with no sound on the phone so you don't know if your are on hold or the call has been dropped. This is just pathetic. Useless company. I now want to cancel this line but I still need to sort this out so i don't end up with a bad credit report for non payment.