Well, if you are paying for, you have the right to complain at the moment to they correct their mistakes and on the future do not happen it again.
I've never experienced a problem. If I do have an issue with a restaurant I like to tell them when it happens so it can be properly addressed.
I've always had a pleasant experience. I agree with with Gavin, return there and I'm sure they would be happy to help.
Perhaps if you weren't satisfied you should not return to the restaurant.
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