First of all, we don't really use work titles when we call for someone. Second, we don't use "herr" anymore since it's too formal. If you want to get in contact with the waitor, you say "ursäkta" and raise your hand. You can use "du/dig" to the waitor if you want, not for calling for him, but when you are using him as a subject or object in a sentence. Servitör or kypare is the word for "waitor". Or servitris for waitress.

Man säger servitör, ja :)