Bad Service Ackermans Quagga shopping center!

I bought clothing items via online shopping at ackermans. However the item was of a smaller size . I went to ackermans at Quagga shopping center to return the item that did not fit properly. When I got there I provided them with the delivery note that came together with the item. The store manager then requested to see the invoice, I then showed her the invoice on my phone as the invoice was emailed to me by ackermans online shopping. She said, she is not going to exchange the item, because she required hardcopy of the invoice. I then told her hardcopy invoice was not sent to me and that they could have at least added it to the package just as they did with the delivery note. She then said that she will not process my exchange unless I go and print the invoice with my own money. I felt inconvenienced , considering the fact that they could have printed the invoice together with the delivery note. perhaps Ackerman's should notify its customers that you will need to print the invoice in the event of exchanges and returns.