Late allocation of funds resulting in extra charge

On the 13.11.2015 i carried out and immediate transfer of funds from ABSA to FNB to pay for flights however FNB suffered a banking problem which resulted in the funds not being allocated immediately. The funds where only allocated on the 20.11.2015. Since the funds where not allocated to the supplier on the same day, they could not confirm the booking. Naturally the price of flights will go up as time passes and once the funds where allocated i had to pay a further R1837 to secure the flight. After confirming with ABSA that the fault was not on their side I sent a complaint to [Email Removed] on the 2.12.2015 and received a response on the 3.12.2015 with reference number 907336NF. I have called ***as indicated on the mail however each time i call i am told that they are looking into the problem. The time delay in solving the situation is unacceptable from an institution of this nature. Since the delay of payment allocation was caused by FNB, FNB needs to pay the R1837 back to me.