Humiliation, mistreatment!!

On Saturday I went and bought stuff at Edgars and paid and when I got to the door the security stopped and asked for my slip and items i had bought which I gladly gave her. Then she ticked and as she did that she said one of the items was not on the slip so I told her that I don't know as I'm from the till and everything in that plastic was packed by the cashier. So she proceeded to ask if I am willing to pay for the item.I got very upset and asked her what she means by that. Another security guard came and escorted me to the till and the cashier said she did scan the item in question and doesn't know what happened and apologised. At this point I was in tears in front of my 2 year old daughter who was very upset to see me crying like that. The manager was also at the till and I was just hysterical.I must say I am not pleased with how he handled the matter, he just took my name and number and haven't heard from him since. Another thing which made me upset is that while i was being interrogated by this security guard, a white lady came out of the shop and she didn't ask to check her stuff.