bad service

I bought a 2 piece pyjama that was on sale at the Claremont branch it was nearly closing time the lady that served me was in a hurry to catch her bus as she was taking the hanger out I asked her to check if the bottom was the correct size it looked a bit big for a small and she confidently rep**** that the bottoms are big makes only to see when I got home that the top is a small and bottom a large then I went to the branch in v&a waterfront for an exchange where I was told to go back to Claremont and their reason was that maybe they still have both sizes at the store, is it not their return policy that exchanges can be made at any branch