I am a client of Nedbank

I am a client of Nedbank. I transferred in error an amount of R2850 into the a wrong account number at FNB. I tried to get Nedbank to recall the amount and got a blunt answer that because I made an instant payment the amount cannot be refunded. What are they their for and what stupid rule is this no refund for instant payment? If I don't get my money back I am going to the CEO Mike Brown.