In your favor:
the woman's faith might be strong, but there's no reason to force it on you. i'd say talk to the manager and ask her to keep the girl in check

not in your favor:
the sandwich charge might not be because of your faith. it might simply be that they figured out you were trying to get a veggie sandwich cheaper than they're suppose to sell them.

neat trick on how you were doing it, but... they may have had a policy on that, or perhaps a recent company memo.

it may have nothing to do with your faith whatsoever.