Stop *****ing Telkom

I have tried to change the date on my debit order to the last day of the month for two months now. I just called Telkom now and the lady seemed confused and could not help me. The current debit date is a problem as there are likely to be no funds in that account by the 19th of any month. Kindly change mey debit order date and stop trying to make money on late fee charges.