It's odd. I've had the exact same experience at two different locations. Both times, I've had an appointment. Both times, they were running considerably behind and I waited an hour past my appointment time. And both times, the techs were extremely personable and apologetic about the wait time.
I get that emergencies happen (which apparently is why they were running so late). But I have things to do too and making me wait an hour past my appointment time makes me an unhappy camper.
The solution seems easy. Call the people with appointments. Let me know you're running late and by how much. Give me the option to get other things done OR at the very least, prepare for a long wait.
This doesn't seem hard. What am I missing?