MTN customer service non-existing

On the 1st of Feb MTN debited my bank account with R2 526.00 while my actual top-up contract is only R309 per month!!! This is a "top-up" account hence the bill should NEVER be over the R309????? So i called the customer care line and they apologized for the mistake and promised to reverse it but every time i call they have another excuse why it has not been done. So this leaves me R2000 short for the month which could for some families mean the difference between eating or not while waiting for them to refund the money!!?? To make matters worse, they claim that they do not have the contract details and will only refund R1900 and some change because thats all they see on their system. This is absolutely unacceptable customer service....very poor MTN!