Debiting on the incorrect date

Good day,

My debit order agreement with Hollard is the 25th of every month however it seems that this month (November) Hollard tried to debit on the 22nd and due to this I have incurred bank charges due to insufficient funds. I got a call from one of the consultants who informed me that this happened due to a system upgrade. Please note that you guys debiting on the 22nd was not the agreement therefore should not be liable to be paying bank charges for an error that was not committed by me. Furthermore, the lady I spoke to informed me that someone would be getting back to me in the next 2 days .....its now a week and nothing from Hollard. I've sent my bank statement and still no response from you. Come on guys you honestly can do better! My ID number is ********** 503088 Debit order reference is Hollardpfs ********** 4s