Rude Nedbank Security Guard

I'm extremely livid. I went to the ATM this morning (Potchefstroom Mooirivier Mall ) to make a couple of withdrawals from my accounts, while I was busy the security guard told me to move aside and give other clients a chance to also make withdrawals as I was not allowed to "hog" the ATM by doing multiple transactions. Mind you, before I approached the ATM there was an Indian male who was there before me also using the ATM doing multiple transactions, I even left him there when I was done with my transactions. I asked the security guard why he didn't ask him to move aswell and for him to show me where exactly is it written on the ATM that I'm only allowed 1 transaction at a time. Not only did he do a back and forth with me he had other clients also attack me because he was getting frustrated. He went on to say that I'm disrespectful and I'm a child. I don't know if this is how Nedbank treats it's clients based on age, gender or race but it's unacceptable and I won't stand for it. I stood in line for my chance to use the ATM, I refuse to be given a time limit of how long I aught to use the ATM. I work for a bank aswell and have been for over 10 years hence I'm aware of my rights as a client. I will not tolerate this kind of behavior and would like this matter to be addressed as soon as it gets your attention.