ok to answer your question, no they are not supposed to take back a core of a different caliper, they can actually get in trouble for that. And i know as well as any one else that not all parts stores and people for that matter are created equal, there are some real dumb peolple out there, and most of them shouldnt be walking into or working at a parts store. But on that note, as far as Advance Auto parts not living up to their name, i guess that you just didnt go to the right one, because at my store, i make sure that everyone opens the boxes up and checks to see whats inside of them, and believe me we know the difference between the right and wrong caliper.