A very frustrated customer.

I am beyond frustrated with the staff from Pick n Pay Workshop in Durban. My baby sister was coming from school in the mid afternoon and in her bad she had a pack of biscuits that she bought at Boxer in morning. So after school she passed by pick n Pay Workshop Durban to buy Vaseline. She went on usual and paid. Security checked her bag and found the biscuits and my sister tried to explain that she had forgotten the biscuits were in her school bag. She asked the security to check the cameras as she didn't have a receipt. She was that humiliated by an Indian manager together with the securities Infront of the customers in store. My sister is a traditional healer by calling. She was also called by names regarding that and also when she started crying the manager said to her to wipe those crocodile tears and go pay for biscuits. The cameras were there, the security black lady refused to look at the footage as she said she doesn't have time for that. My sister was brutally insulted publicly by pick n Pay staff. I would like to take this further as my sister has never ****** anything in her life. Now she's even scared to go to pick n Pay due to how the staff treated her. All of this was kept in camera. I would like to take this further. How do I go about this? I need answers immediately on how to take this further because I will not let it go just like how my sister cried the whole store and was embarrassed. Imagine, a whole ****** big business like this. We've never has any issued before as we always buy from this branch as it's closer to transport. I need answers, immediately.