Worst service experience

I went to pep home delmas stote code 5648 to buy a paxi return bag for avon products. I got there and explained what was i looking for instead the cashier sold me a wrong bag sealed it and only told me when she was done that she didn't know how avon returns work and now i cannot gt my R60 back since the bag is used. I am furious with her service there, she didn't call her manager to try for a solution nor did she apologize . Instead she stood there as if nothing was wrong.