yeah some people can really suck when it comes to time management.
Some of your examples though seem to me like there's two sides to the story.
The girl that said she'd call back in two minutes. Maybe her mom needed more help than 2 minute's worth. Or maybe they got so busy, she forgot. That's not such a bad thing.
If you really needed to talk to her so bad, you could have called after a half hour or so and gotten the story.
You never made a set date/time for the Clerks 2 girl, so that's not all her fault.
If you had more definite plans with her, I could see getting a bit more upset.
I'm not saying you're not justified in how you're feeling, though, so don't get me wrong there.
If it's really an issue for you, and they're really your friends, then you should talk to them about how they're making you feel when they treat you like that.
You should probably also work on lowering your expectations. Things happen, not everything can work exactly as planned all the time, so you can't let it get you down too much.
Yeah it's frustrating when it seemingly happens every single time, but do your best to work around it.
Talking to your friends about it will help a lot, as a start.
