MTN won't accept monthly contract payment and just cut us off instead.

We registered a new credit card as our payment method for our MTN contracts four months ago. The card is active, we use it on a daily basis. For some unfathomable reason, MTN did not withdraw our monthly payments as they used to. MTN also did not let us know that they were not receiving payments. Instead, they cut our service off with absolutely no warning. When we phone the MTN customer care line, we were told that they cut our service due to non-payment. They also said that they "had not activated the credit card on their system", which makes no sense. We asked them to activate it and withdraw the outstanding payment. They have yet to do so. It's been a week. Why won't MTN make the withdrawal and reconnect us? This is horrible service and I'm absolutely shocked and appalled by MTN's utter disinterest in serving its customers.