It's too late to worry about what you "should have done". I'm not
sure myself. I think I wouldn't have raised a fuss until I saw them
actually making and serving sandwiches with the mix that had glass in it.
At least, you could have given the people who got glass in their food a
piece of paper with your name and phone number. I'm not sure what the
health department would have done.
But for sure, never go back to The Bread Company again, and thanks
for warning us. They obviously have very very stupid employees, and other
health and safety violations probably occur daily. Glass in your mouth at
least gives you fair warning. Bacteria aren't so evident, and can be more
deadly.