No clear help given

I had a payment arrangement to pay on Tuesday, 6 April for X amount. My salary was messed up by FNB and it is now being investigated so I could not pay. I now borrowed money to honor the arrangement. Call center agents suddenly give different amounts. 2 amounts that was different from the arrangement. They also give other conflicting info. Some tell me the additional amount is only due end of April and some say ALL is due now. The last agent said MAYBE my account will be opened once the arrangement is honored. They say the "new" system now dictates what happens and that it can't be over-ridden, not even by a supervisor. I need to do a sim swop so that I can use my number again so that work can contact me. It is not as if I am going to run away without paying. I do not want to have to go to another provider as I have had my MTN number since about 1999. PLEASE can someone help me?