Over Charging to reserve payment

On Saturday evening I made an EFT Payment of R150 to a Standard Bank Account but accidentally entered the wrong account number. Realizing today the account number was incorrect( as the person had not received the payment yet) I contacted FNB to reserve the payment, they then informed me it would cost R265!!! It would cost me R115 more to reverse the payment then the actual payment. And if the account number didn't exist and the payment didn't actually go to anybody FNB just gets to keep the money. How is that far? How can FNB charge so much for simple human error? Surely you should only pay a percentage of the amount being reversed if anything. FNB really let me down today which is highly disappointing as I am always promoting FNB to friends and Family for fair and great service.