Contemptuous cashier service

I am disappointed. This morning I got an ewallet notification,and without wasting any time I went to SupaStore in Rockville to purchase certain items. I got to the pay point and the cashier tells me she is afraid she can’t take my R100 note and if I have another (I didn’t) because the one I had just withdrew had a stain/ink. I was puzzled because it was not my fault,I even showed her the ewallet sms I got and told her I just got it and there’s nothing I can do. The cashier told me if she takes it the ink will get her in trouble,I asked her if she could run the note through the machine that authenticates money and she did but still didn’t take my money. She even asked for water and sprayed the note in an attempt to see if she could wipe the said stain off. She made me wait on the side and said that she will help one customer and help me after asking her manager and gave me my money back and my contents. I waited and watched her help 2/3 customers without her calling me back or calling any manager for help. After a while I signaled to her and she contemptuously asked a manager waiting on the side to talk to me,I explained to the lady what the cashier had said and she helped me. What angers me is the contempt she treated me with,I am an innocent customer who didn’t know what to do and I am disappointed in the way she handled me. I’m a fan of SupaStore for their efficient service and affordable prices,but they could handle some situations better.