And, wow! That's pretty ballsy of them. I worked retail at one point and I would never
have said that to someone, even if I thought it!
Good for you for calling her on it! Seriously, you've got to show people they can't treat you that way, you don't deserve it. When store people are getting too far in my space, I always smile and say, "When I need your help, I'll let you know." That gets them to back off pretty quick!
ETA: If they're really rude, I've also been known to ask, "I'm sorry, at what point did I ask for your opinion?" But, that's usually reserved for someone who's shockingly rude for absolutely no reason. I'm not a witch for no reason!! Haha!