unable to make calls

Ever since ive joined MTN my experience with them have been an absolute nightmare! For the past week im unable to make outgoing calls despite having airtime, calling the call center frustrates a person to the core with the agents sarcastic answers and no interest to help its customers. my encounter with Noxolo Khumalo this morning was just the same. i explained to her my problem she then gives me a code to dial which still does not solves the problem and when asked why am i unable to make calls she gives me a sarcastic answer " i dont know how you use your phone" !!! this is how pathetic mtn treats its clients. AND IM STILL NOT ABLE TO MAKE CALLS