Cannot get a refund for a factory fault on a dress

I bought a dress for my daughter's matric ball at Yde Canal walk however she decided that she did not want the dress anymore as she saw another dress that she liked. I returned the dress at Yde in Cavendish. The lady took the dress and my slip , ask for the card I bought the dress with which I gave to her. She than proceeded to inspect the dress this took almost 10 minutes. All of a sudden she says she can take the dress back I must take it back to Canal walk as there a small tear in the dress which I never saw. I explained that the dress was never worn as the matric ball is December . She than says that they were not suppose to sell the dress to me in that state and they should have inspected the dress before selling it to me. However to my thinking that is their internal issue and I should still be able to return the dress at Cavendish as it is a factory fault. I returned the dress today as I am only off next week Sunday again and than my 14 days will be over but this lady did not want to understand this. Please advise what am I to do now. I which I read all these reviews before I even attempting to buy anything at Yde as it seems it is impossible to return anything at this store.