Picknpay tsele disaster

I went to picknpay merafe in Soweto today and I was treated like a *****. I bought 3 items and the cashier somehow didn't punch the cheapest item that I bought. I got to the passout door and was stopped by the security guard who questioned me why the item was not on my slip. I then checked my tillslip and realised then that the item was actually not paid for. The security guards made a huge big deal of it and I felt embarrassed as it was as if they believed that I had ****** the item. I was made to wait at the door by the security officer while he was busy checking I don't know what at their office. How is it my problem that the cashier made an honest mistake which could have been rectified on the spot? I stay few blocks away from merafe and I'm not going back there again