MTN "system error" costing me money

i have two lines at MTN SA, both go off on debit order after the 25th of each month. Why September should be any different only they will know. On the 2de of October I received a SMS saying that my account is now a cash account and is unpaid. Now look, I am a busy person so I trust that my debit orders will go off as they should. But now my account will be suspended due to and I quote " a system error" and a double payment will go off end of Oct. The amount of times MTN has let me down is astonishing and I have had it. How does one win in these situations