That must have been an awful situation for the people to be in, i can't imagine having to do that. My vets have occasionally kept people waiting, and used the vet nurses room for situations like this, and I have used their back door at times when I haven't been able to face going through reception (I have also been allowed to either pay in advance or get a bill - I personally prefer paying in advance, it was awful getting the bill for that through the door a week later). If I know for definite what is going to happen, I ask for the latest appointment, so I am not rushed, and dont have to face people, my vets are good at giving me 'special' appointments (right at the end, when tehy dont normally book people in).