bad service

I just had a bad service from one of the Multi choice staff member in Springs branch her name is Thuli, I paid last month their machine could print slips she said it's fine I can go , a week later I was disconnected went to complain she said I must give them bank statement which I did, stating only the payment I made to them . No she said she wants to see my monthly statement showing all payment I made to order people. I don't understand why she wants to see all my transactions while the one I gave her shows exactly what she is looking for. Now she is telling me their is nothing she can do. Is this how people are suppose to be treated after taking their money , I feel people who are sitting behind the counter feels they have all the powers to say or do anything to others.