Refusing to assist

I went to Mc Donalds at Cresta Mall on Turesday 26/11/2019 only be be treated as though I'm dumb the Supervisor tells me that I'm no allowed to order at the till and that I'm suppose to use the self service machine. I tell her I don't want to use is cause of particular reasons (in which I had an experience with before else where) she doesn't ask me why instead she insist on showing me how it works I tell her I know how it works but she tell me I clearly don't know and the till is only used to make payment not take orders. And I told her there is no such thing on Monday I ordered at the till cause it was full the lady assisted me then suddenly yesterday I'm told u don't buy at the till. The supervisor kept implying I'm clearly dumb and unable to use the self service system she clearly refused to hear what I had to say let alone assist me. the service at McD is very bad and they don't care about they clients