Terrible customer service!!

Very unhappy with Mr Price Sport at Fleurdal Mall in Bloemfontein, bought aqua socks last week, they said they will email me the slip, but the email never reached me. The aqua socks was the wrong size, and when I went back today to exchange it to another size, they simply refused because I didn't have the slip! I told them that they didn't send it to me, but they just say that they printed me the slip last week and they refuse to exchange the aqua socks! But they didn't print it, had to enter the email address where they should send it too, but they simply don't believe me and is adament, they won't exchange the socks. Even spoke to the manager but to no avail! Now I have an extra pair of aqua socks which doesn't fit me but for which I had to pay due to the terrible inefficiency of Mr Price Sport Fleurdal! Won't shop there again!