Daylight ******s....

I have been an fnb client for almost 7 years. I pay my monthly fees every month plus extras. 2 weeks ago I went onto Hollywood bets and tried doing a card purchase for R100 but mistakenly entered R1000. It went through. I was under impression you guys granted me an overdraft thats why it allowed...so I did it for R4500. A week lata you guys tell me I'm in arrears and you will take legal action. Charged me over R1500 in fees. That is not fair. You guys allowed me purchases so how is that my fault. I want these charges removed. I dep R5658 yest. I hate what you guys did....remove all those ridiculous fees or im switching banks!!!!!!!