I had a similar thing with a Marc Jacobs bag that I'd been using almost SIX WEEKS! While I did order it online, I called and told them that the wearing of the leather on a $1200 handbag was totally unacceptable and I wanted to return it. They said no problem, I returned the bag per their instructions and got my money back.
The SA is probably being a snot b/c they lose their commission when an item is returned. Better lose a commission than a customer, IMHO.
Dig in your heels. If the manager gives you any crap, go to the next level.