Promise/Deliver

Perhaps you've heard of the saying, "under-promise, over-deliver"? Well, it's a good idea, especially when you're monkeying with people's money. Saying, "Well, it's possible we could knock another [amount] off of this rate, and I'll look into that,"
is okay. Calling up later and saying, "Guess what! I found a way to take another [amount] off your rate!" is better. Saying "Oh, yeah, no problem, we'll knock this down [amount], because you're in [category]," when you're not positive they are, is piss-poor. And you wonder why customers call and harangue you - or worse, me - when they get figures that are a zillion times larger than they were expecting. Dipshit.

It was like that in other places of business, too. Just so no one thinks I'm picking on anyone in particular. Computer stores "oh, yeah, that'll be configured in an hour." An hour and a half later... "Er, could you give us another 20 minutes?" Dumb, dumb, dumb.