Poor service i want my money back

I went to Westgate jet store on Thursday to buy a swimwear R300 for my sister, however she didnt like it, today I went back to Westgate jet to return it, it was still in its new packaging, tag still intagged, a very rude cashier told me der will not assist me, i must see what I must do with the swimwear, i left the swimwear at the store because I did not want drama. Please i want to refund n i am disappointed by the way the cashier did not bother with my request he just rudely answered me n said i must donate it if i don't want it. I want my money back please.