"Excuse me ma'am. Could you please bring me the complaints book? I would like to complain about you." I said softly to the rude flight attendant who would not honor vegetarian food, for our 2 year old. (This was over 12 years back and they brought a chicken meal and said that is what they had).
I tried every technique in the book to get our infant, some food. But, none of it worked and I tried politely explaining how we had vegetarian food in the earlier leg of our journey. I even asked her to summon her supervisor. The boss lady was worse than her report.
After that... when I said those words, hot pasta came out of nowhere. If all else fail, politely tell them, that you are going to lodge a complaint about them.. After all they are employees of their company and they have performance reviews as well.
Don't holler...lose your temper...just say it softly.
It worked every time, for me. If it didn't, never go by that airlines ever again...