As there was a line of customers behind you, the desk staff was too busy to be other than grateful that you had moved on, let alone plot to undermine your visit by playing 30 minutes of phone tag to find the correct med school office to report your argumentative behavior to someone who'd probably be in complete sympathy to your plight.
And I'd make a point of writing a letter of complaint to the rental organization so they can better train their phone staff for future contacts.