Incorrect debit order date

I took out covers with Clientelle last year, they notified me in December that they would be running the debit order slightly earlier. Which was fine. They however decided to debit 5 days earlier than the debit date agreed upon in January as well. Which resulted in the bank charging me R413.75 for the failed debit orders and this affects my credit score. I am disgruntled by the fact that I did not give them permission to debit my account on that date. I have contacted their call centre 3 times already, the call either cuts off or it goes quiet. None of them have bothered to call back. They should cancel those policies if they don't value me as a client and I want my bank charges to be reimbursed.