Customer Complaint - Exchange

I was at the Carletonville Pep home on the 12.07.2018. I wanted to exchange 28 place mats for a 100 glasses and was going to pay in the difference. Unfortunately I misplaced my slip. The lady who helped me at the till said she could not assist as I did not have the slip. I explained to her that I do not want the money back just an exchange. Then the manager came and said she could not assist because she has got a stock take soon and that I do not have a slip. I then logged on to their website to try and get help from customer service. I then got a reply saying that I send it to pep clothing instead of pep home. At the bottom of the email I was given a reference number 573349. I still have not heard anything from the store regarding my incident. All I want is an exhange. I do not want a refund