SUSPENDED ACOUNT AFTER PAYMENT ***

I have contacted MTN numerious times to have my debit order date changed from the 25th to the end of the month as I only get paid the end off the month. They still have not done it, so when the debit order goes off, there are no funds. I paid my account IN FULL the end of Sept20 and still my account has been suspended. What do I need to do to have this fixed ***