Always get horrifying service at Shoprite South Gate Mall

I went to Shoprite South Gate, which I hardly go to but whenever I decide to shop their service is pathetic and horrible. I wanted a few things and used the small trolley, they had long queues and joined the queue from the back. The lady whom described herself as the manager came and said I must go out of the queue and find myself another queue after I stood in the queue for over 30 minutes, I insisted to be helped in the same queue, she said they wont help me "YOU WONT PAY" because my items looks more than and I am queuing on the express till. She argued with me until the express teller called me as I was next, I unpacked my grocery which could not have been more than 15 items, she came and packed back my grocery saying I must wait for another teller and the person behind me must be helped. She behaved like somebody who is not trained, nor know anything about customer service.

1. She didn't have her name badge and when I asked her name, she kept on ignoring me. 2.I asked if I could be assisted by her manager, she said she is the manager even after I asked who she reports to with no answer 3. The teller willing to assist me and she came and put back my grocery in the trolley 4 Did the same to other customers behind me whom had to go and join other queues after a long wait. 5. When I asked the teller who was assisting me who her manager is, there was not answer and insisted that I wont pay until her manager comes. Don't know if their manager's names cant be disclosed nor see customers. 6. Eventually spoke to someone whom she said he is her manager, which I don't believe because she still went on with her bad attitude in front of him and **** that she directed other customers to alternative tills. 7. When I asked her name she never gave it to me, until heard other cashiers calling her. 8. Her so called "manager" apologized on her behalf and I advised him that wanted the apology letter directly from her, and the manager said " it will not be possible"

Please advise what are we supposed to do as customers when we experience such service??????I am still mesmerized by her behavior.