Card division has a rip-off plan

In April I used by Credit Card by mistake when I did an ATM withdrawal. I meant to use my Cheque Card but the Platinum cards are both the same colour. So I am now charged R12.50 every month for a cash finance fee although I pay an amount of R3000 to R6000 every month into my account. I phoned the card division and they tell me that when I made the cash withdrawal they opened a cash account and if I want to stop this fee from going thru every month then I have to settle the full balance of R75000. This is totally unacceptable. So now I will be charged this fee every month for the rest of my life and the bank will make more in fees than the R1000 I withdrew. Is this a way that the bank uses to make huge profits from their clients. I have been a client of this bank for over 40 years and incidents like this make me want to change banks. I also pay a huge monthly fee as a Private Bank client and my private banker said that I should not have to pay this fee as I am a Private Bank client but the lady at Card Division says that is not true so I am caught in the middle.