I get stuck in the next challenge to my polite demeanor when I finally do ask for help and the constant wave of unsolicited pant/tops/bottoms, etc. coming flying at me over the changing room door.
I often find the clothes they've pulled for me... hideous. Plus, I've already rejected that item when I was browsing the store.
"No thank you. I'm really fussy and I have all that I need." I feel like I'm insulting their taste when I reject their offerings, but unless I asked specifically to see a Mrs. Roper style muumuu, I would like them to kindly leave it on the rack.
If they can't take no for an answer, I will just repeat "No, thank you," in an increasingly loud and clear voice. My best friend laughs because if I get to a third "no, thank you," apparently my voice is kind of shrill and panicked.