I have that too with guests when they find from a computer error that the hotel has over-booked and often all the hotels nearby are fully booked so the best I can suggest is a park bench by the river (suggest their car?) honest I don't really but I'm tempted. On Saturday nights, pissed and tired people aren't at their best and most polite. Whatever though, it's not your fault, just say 'sorry' over and over to them with an apologetic smile.