That's what they've been told to do, it's not their fault. It's like if you go into a Pepsi venue and ask for a coke, they will always say "Pepsi". Now I just want some sort of cola-flavoured beverage, I'm not that fussed, and they know that, but I don't think "this person is such a pedant" or think I'm being disrespected.

Believe it or not, I actually appreciate this, since if I ask for a Coke and I get a Pepsi, I can tell and my tastebuds are disappointed. So if they say, "Oh, we only do Pepsi," I can say, "Then, I'll have a water," or something.