If the food arrives cold, the fish is raw, the meat is very overcooked, or the server is just plain rude, you definitely have a reason to talk to the manager. Explain what has happened, how it impacted your dining experience, and ask for a discount. In most cases, you will get at least a few of the items removed from your bill. In extreme cases, when everything went wrong, you may very well be told not to pay anything. However, if the server was great in spite of all the problems, don’t forget to leave him or her a tip.