Terrible system

When I opened my contract with Telkom I requested that the debit order is deducted on the last day of the month, which is when I get paid. But they have tried deduct it on the 25th, and obviously it bounced back due to insufficient funds. I went to my nearest Telkom store to correct the debit order date but since it takes 30 days for changes to go through on their system l, they tried to deduct my 2nd payment on the 25th again. And of course again insufficient funds. So not only do I have to pay bank charges for insufficient funds but Telkom charges R200 each time you have insufficient funds to pay your account. I again went to their store to correct this but apparently there is no way to reverse the R200 x 2 Telkom charges for insufficient funds, even though it was their mistake.