Can people be treated like dirt in a work place

A very dear friend if my mom's (my aunt) was recommended for a casual job. From the first week she told me that she thinks the person in charge does not like her because of the way she is being treated. She felt that she did not get sufficient. When capturing data on a live auction my aunt makes a mistake this lady would shout at her on the top of her voice "what are you doing, get up, get out of the chair" and this would go on the entire day. She felt as if she was treat a disobedient dog. When speaking to my aunt she system crying the way this woman treated her. A few weeks later a new casual started and my aunt sat with them while this woman trained her. According to my aunt she spoke very softly to her and when she made a mistake she would say "no my dear that's wrong this is how it must be done" or "no my dear you are on the wrong lot number" no shouting was done. This casual person also told my aunt that she use to come on a non auction day to practice. When my aunt made enquiries she was told that training was only done on the live system, I'm not sure who is tell the truth. There was on occasion she was relieving my Aunt's partner the auctioneer said that they are going to reoffer lot number ??? She clicked in that column this woman shouted kn top of her voice to my aunt's partner "she making changes quick she what she us doing". The auctioneer looked at her, my aunt, the person sitting next to him shook his head said something to this man turned back to the buyers and said "we going to reoffer lo number???. When a second casual started she got the same training as fhe first casual from this woman. On their WhatsApp group she messaged all the casual staff that work will be rotated but my aunt never got as many shift as the other casuals. At the start the 2024 a message on WhatsApp she asked who was available to work and welcoming a new casual, everyone except the first casual said that they were available. For most weeks January and February there has been actions on a Tuesday's and Wednesday's and the same 5 people work every time. Every Wednesday night my aunt has dinner with us and without her knowledge I look at the Webroute WhatsApp and look at the messages. I see messages from this woman to the group about mistakes they are making and telling them to stop the auction and rectify the mistake these are the same mistakes my aunt was making that this women shout at her for making. I am not sure if my aunt is being discriminated against because she is coloured and all the others are white including the staff of the auction department or if it because she was recommended my the CO'S wife. According to SARS a causal can only work 24 hours a month but these casuals are working between 50 and 60 hours a month.