I've noticed that some providers don't feel the need to abide by common courtesy and return phone calls, emails etc. or notify clients when they can't make it. And my number one peeve - let you show up and then don't answer the door or the second phone.
Haven't personally had that happen in a long time but still pisses me off.
Having said all that, I just chalk it up to immaturity and Don't Ever Call Them Again!!