I'm so annoyed, just had to post about this. I received a gift card to Mijana in Burlingame and went for lunch. The waitress asked me if I wanted my lamb with rice or as a sandwich, and I said rice. It turns out that's the dinner entree, and it's $10 more. She didn't tell me this when I ordered.
I went again (still had money on the card). The menu says you can get three cold appetizers for $9.95 or three hot for $11.95. I asked if I could mix it up - waitress says sure. (Apparently I have a learning disability, because I didn't think to ask, "How much will that cost me?") Again, it was way more food than I needed and was $23. I asked the waitress about it when I got the bill, and she said it was more expensive because I had two hot appetizers and one cold. I would have created a stink if I was paying for it, but since the gift card covered it and I didn't want to go back anyway, I let it go.
I understand why making substitutions on a meal deal costs more - it slows down the kitchen to make special accommodations. But that's not the case with choice of appetizers. If you're going to be a stickler about such a policy, you should let diners know when they order.