MTN stop my phone inadvertently- system error

So my apple phone stops working today, “unable to make calls because my limit has been reached” I am told by the call centre. When I asked why I had a limit, was told that THE SYSTEM had reduced my shadow limit inadvertently but not to worry she would transfer me to a credit controller to reinstate this limit. Wait 15min no answer. Phone again, transferred a 2nd time, wait 17min no answer. Still unable to use my phone!!!