Disgusting

I bought nappies for my daughter at the Dischem at Haasendale, I took a size 5 and it was on special for R159. Saturday that past I needed to change it for a bigger size, a simple exchange you would think would be easy, hassle free. I went to Zevenwaght mall Dischem to exchange it and instead the lady gave me a refund, I asked her why she did not do an exchange she said no the price is now R209 and that I must pay in a 50 to get the size 6, its a new month and its not her problem I must pay in. I were very angry and said to her this isnt right this is not how you do an exchange, instead she was adamant that she is right when I told her that is not right. I left after I paid, 10mins later the admin manger called me saying I must come back to the shop so I did and before I could speak she said she apologize for the colleagues mistake and that it should have been an exchange not a refund. What kind of **** service is this??? The lady that made the mistake stands there and said nothing she doesnt even apologize its my time to come back again for your incompetence