The easiest solution for this would be to also allow the rooms to be booked through online chat, which the librarian at the desk could monitor. It might take them a couple of minutes to get to you, but it would provide the same speed of service as the phone. (But not switch to that because for somebody with dyslexia, the chat could be as annoying as the phone is to you).

It's not that hard. But I think the deeper issue here is the rampant buckpassing, like wow...