Horrific treatment

I am at Makro Centurion to buy groceries and as soon as I am done I join the que as it starts at the back by where they pack the vegetables. 20 minutes into the que I get closer to the till. A staff member tells me to go start another que as I am queing in the wrong que. I tell him I will not to that as I I started the que from the back and he saw me why didn't he advise me to join the correct que. He says I can continue to que but no one is going to assist me at the till. I tell him he must call his manager as I cannot stand in the que now close to 30 minutes to be told I am standing in the wrong que. He in deeds calls his Supervisor by the name Alex\Alexis (Caucasian blonde female). She is extremely rude and tells me to learn to read and look at the board on the wall as it says less than 5 items. She says I am wearing glasses therefore I should have seen that Disclaimer from the back of the que. I got extremely angry as she is telling me this in front of other customers, is it because I am black so this means I cannot read or make sense of something I didn't see when I joined the que from the back with people who have more than 5 items in their trolleys. I told her she must find me a till I can pay at as I am not queing and living my groceries. She took me to a till where staff members can purchase their items and she was extremely rude to her staff as well as she told them to get out of the way and that they are not allowed to fill their trolleys. Is your supervisor usually that rude or she only does it to Black people. Her stating I must learn how to read is a very ****** remark. Her treating her black staff like a broom to sweep filth is very upsetting to me. If you font respect me as a customer how do you treat your staff at the Stock room. I will tell everybody willing to listen and I will put this complaint on every social media platform so that your customers to know you have someone like Alex\Alexis working for you. The only thing I regret is not taking a video when all this happened.