I had an issue several years ago and it was the food that wasn't up to their regular standards and the manager was very helpful and very understanding and I walked out with more respect for the people who do their best to keep the place great.
Voice your complaint to the Kitchen Manager. They will welcome your respectful feedback.
I try to address the problem before I leave the restaurant. If that can't happen call and dorsal to the manager.
Call and ask to speak with the manager.
Complain to the manger over the kitchen
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