Pick n pay Tseles disaster

I went to pick n pay tseles in Soweto with my son today and I was horrified by the service that I got. I bought few items and was even having a friendly conversation with the cashier like I do at most stores. I took my items, change and my tillslip and when I got to the passout door my shopping bag was searched and I was asked by the lady security guard where is 1 of my items. I took the slip and only realised that the cheapest item was actually not on my slip. She called a guy security guard and told him. I told both of them, please ask that cashier that I paid at cos I need all these items. The guy went with me to the cashier in question in full view of all customers and worse part, my son. He got there and just stood there instead of explaining to the cashier why we are there, and I had told the guard that he's actually wasting my time as I need to be at work as he also first said to me that he's at work and "doing his job". I had to explain to the cashier that I'm being refused to leave the store bcos the item was not paid for. The cashier apologized and I was willing to pay for the item on the spot. The guard told me to wait at the door as he needs to go to the office to do, I don't know what. What pathetic service is this? Can I ***** the cheapest item out of the only 3 items that I bought in store? My son kept asking: " Ma, what's going on?" I walked to one of the supposedly supervisor and explained to her what had happened. I ended up leaving the item there bcos it seemed wrong for me to have what I went into the store to buy by the security guard. Such simple mistake by the cashier caused all this delay and mess. I hate the humiliation I was put through.