Taking away rebate unfairly - Private Banking

I have a Private Banking Cheque account at FNB. My salary was deposited into my account on 27/11 and I have paid a few accounts after I have received notification of the deposit, of which I have an email sent to me at 02h40 as proof. I then proceeded to do a few transactions from 7h30 onward. Great was my surprise when I checked my transaction list today, and found that I went over the limits supposedly, as the salary was only added later during the day. This now means I will get NO rebate this month - about R600 rand worth. I then called the Private Banking helpline - Ref Rl***~3, and they had no answer for me, except that yes, I have lost my rebate. And this while I have an email proving that the deposit was made way before 7. I really expected better service from Private banking at FNB, and I hope that this matter can be settled soon, as this is not the usual service I experience from FNB