Try the manager first. Give him an opportunity ti address and hopefully resolve your issue. That's only fair. if you were the one in charge I'm sure you wiuld like to have the first chance to turn things around. If you get satisfactory results, great! If not, then review sites are the next step.
Or write a Yelp review. Restaurants look at them and so does the general public
While you're at the restaurant, talk to the manager.
Call the manager
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