I went to the apple store to use their screw driver in order to tighten up the bottom plate of my rMBP and you know what they said? You need an appointment. Terrible customer service! Eff that! So displeased with their unwillingness to accommodate...
Apple has an excellent system in place, that assures they are able to serve as many people at the genius bar as possible on any given day.
They've made it easier to setup a last minute appointment than any other retail sales & service facility. If you go to Apple.com from your computer you can see their schedule on any given day including the day you log in, and using your Apple ID, make an appointment.
They also have an app so we can make appointments from our iPhone. No one else has this level of convenience, and organization.
It's up to the owner of Apple products to take a few minutes and learn about these conveniences. If one just assumes, they have an experience as you did.
Being the successful busy company they are, the system they use is ideal.
I understand you wanted priority attention, but they have more things to do, than to work on a random basis. Next time you'll know.