Stephanie47 Nikki made a few good points so not off base really IMO.
Voice inflection and tone do make a difference but you don't have to fall to their level in retaliation or dare I say be a prick back to the store person.
That alone will put you in a bad light but going to the boss via email or make a phone call is the more appropriate way to handle the situation and actually get something done at the store level.
Nobody likes an activist all up in their face demanding things, we all know that doesn't work because its being intolerant in a way even worse than the intolerant sales person.
Thick skin and a I could care less attitude is the way I deal with things but that is just me your mileage may vary.