I've gotta agree with K-loc here.

Make the girl come and find you, when your out drinking, shopping, college or what ever tell her where you will be and tell her to come see you if she is about and maybe you can get a coffee/meal or something. I'd do this esp with girls who have let you down in the past.

It stops you from looking so desperate and also if they do flake so what? carry on drinking with your friends or finish your shopping.

_________________
Tony T

Good, you spotted what you're doing wrong, when you couldn't before

Yes I have had to learn to deal with anger too. It's nothing serious of course, but in the past it has made me say things I regret, and I look back on them and think "WTF was I thinking??" now I'm more easily able to catch myself than before, and calm down.
1. if you're gonna confirm, do your best to make it a funny message. Personally, I like puns. Or at least some upbeat message. Or some additional info, like - "I'll be waiting under the big red sign "
...haha - "Reddy and waiting " told you I like puns.

2. That's a perfect plan B - the best one for any situation I think . I just had one of the best darn nights (there were some ups and downs but boy did it end on a high once I got my shit together) and it was all a "plan B" - I was hoping to meet some girls at this hippie club again, but they didn't show up tonight, so I just started gaming. I ended up with the phone number of a very keen young Jamacian girl... wow... she totally wants to go dancing classes with me in a few days.

STOPPING FLAKES
Text morning of meeting - “I’m gonna be 5 minutes late, just so you know, terribly sorry”

That gives her a chance to back out and tell you she's not coming. That stops them and lets you know without showing up to the place looking like an idiot. But if it keeps happening you need to change what you're doing.

Credit - AFC Adam

What would u accomplish from this? And why would it piss you off?
Learn to speak with your objectivity, and dont let your emotions drive you.