Pep courier no refund policy is inconvenient!

I went to pep cell Elukwatini this morning to courier a parcel. As a first time user of the courier service, I bought the wrong packet (instead of the R100 one I bought the R60 one) because the cashier did not explain the difference between the two packets to me. Only when I asked about when the parcel will be delivered, she informed me that the packet I bought was for delivery within 7 days. When I asked her to void the purchase, she told me that she can't because the sale has gone through. Since my parcel had to be delivered urgently, I proceeded to buy another packet whilst hoping that the cashier will come with a solution. My parcel is now sent but I need a refund of R60 for the other packet. I've left the R60 packet plus sale receipt with the cashier hoping that she will resell the packet to another customer during the day. Before I left Elukwatini I check with her if she managed to sell the packet, she said no. I stay far from Elukwatini, I was just visiting for the day. How do I get my R60 back?