What about a contractor that tells you that he'll come this week and calls you sunday evening telling you that he expects to come somewhere next month? That is unacceptable!

It is, but when he calls you back and says that we'll have to reschedule to the end of the week, probably Friday (i.e. the change from end of summer to September) and you start to panic Monday thinking that he isn't here today and wondering if he's going to come at all - you need to relax and realize that he wasn't going to come today. Start to get upset if he's not there on Friday, or for when you rescheduled.