Disappointed with the service

Hello, today I went to Sheet Street in Orange Farm at Eyethu mall and was surprised when I was going given R100. 00 change instead of R100. 10 without any explanation, what concerned me is how Mbali(MBMAS) as per the receipt told me how she doesn't have my 10cents change when I asked for it. It was after she asked for the 10cent from another customer who seemed to be their friend like it was nothing that made me realise how she does not know or wasn't trained about customer service. How many more customers is she not giving their change without explanation and why is she running her till without enough money to give change to her clients