Save Supermarket robs people

I was doing my shopping at Save Supermarket Durban West Street last week. When I was about to pay at the till the with R100 the lady shouted that my money was ****. I told her that impossible because I withdraw the money from the bank. She than called the so called " manager " they came with R100 that's looked dinferent from mine which is the **** one. They told me they can't give me my money I will have to come with the police. What is happening is they robe people money by claiming it is **** and refused to give it back threatening they will call the police.