Returns disputes

I made a purchase at Forever New inside Edgars Sandton City on 2 Dec, both items were stained and one of the dresses didn't have a label at the back, I told the sales lady that I will not fit the dresses in store as it was late evening, however I will return one, since I only needed just one dress but was not sure which one would go with my shoes...etc ! on 6th Dec, my sister returned the one dress, however she was told they can't accept it since it had a stain and didn't have a label at the back, the manager then told her to c ome back on 8th Dec when the sales lady was back from her day off, I went to the store on 8th Dec, to complain and return the dress, however the ladies told me the same story, and the sales consultant denied that the dresses were both stained and one didn't have a label at the back. I then left the dress and all slips with them nd to this day, they haven't credited the sale back to my account. QQ - how I could've ignored the rules around return policy and also they implying that I wore the dress, however I have been out of country from 3Dec - 6 Dec late evening ?