I don't think, generally, that NCNS works both ways. GENERALLY, hobbyists have to plan for an appointment, and have to explain (or.plan not to be asked) where they have been. GENERALLY, a provider, if she is full time, already has a schedule she doesn't have to explain.
I will be happy to post links tomorrow, but I read at least 2 NCNS reviews tonight before I ran into this thread. In both cases, the hobbyist was with 30 minutes of arrival and the communication stopped. That isn't NCNS, that is pure flakiness.
Not flaming anyone in particular, but it amazes me how many providers have so many things come up at the last minute. If I ran my business like that, I wouldn't have a business.
If it seems like this issue gets under my skin, it does. In summary, a few months ago, I posted this:
http://www.eccie.net/showpost.php?p=895845&postcount=5