UNPAID DEBIT ORDER

I took out a personal loan with Capitec around 4 years ago, and it will soon come to an end and be settled. I have never had this problem before at all with any other credit provider, but in the last 3 months Capitec attempted to take their debit order off my account earlier than the date as per the loan agreement, which is the last working day of the month. Even this morning I got an sms notifying me of an unpaid debit order from last night!! The last working day is tomorrow, the 31st. There is no possible reason that you people can give me to justify you putting in the debit order earlier, and now because of this, my credit record has been affected and I have been unable to receive credit from other credit providers because of Capitec's mess!!! I even told these other credit providers that it was not my fault but they said it doesn't matter, even if Capitec provides written confirmation that its a fault on their side! What the hell am I supposed to do now??? Do you people know how much of a hassle it is when trying to get credit elsewhere and then being refused because of your stuff-ups?????? And the exact same thing happened to my sister too, more than once!!