debit order date

I am very disappointed that my debit order with discovery has been messed up. My debit order is normally the 25th of every month, sometimes the 26th. November month discovery decided to debit on the 23rd November, don't know who gave them authorisation to do so but obviously it was unpaid as it didn't get paid, they contact me and then I was advised to make a transfers or deposit, I told them they can double debit me on the 23rd of December as I will be getting paid early and there is a lot of public holidays in between. Cecil called me this morning demanding that I make a transfer and a promise to pay and more worried about his PTP then the wrong that was done to the client, why must I make a transfer or go to the branch if my banking details are available for you to debit my account. I am utterly disappointed in the service provided and will soon be finished with you. I will never recommend anyone to discovery.