So? They have one hour when they're there for students and then are pissed off because someone comes along close to closing time? They are there for SERVICE, for goodness sake. They have no damn right throwing you (or anyone else for that matter) out just because it's nearly the end of their workday. Especially when they fucked something up. How DARE they to not believe you?

I could rant for ages about the insuffent organisation that calls itself university. *growls*