Don't you hate when customers get all belligerant and give you shit about things you can't change? Don't you wish you could DO something about it? Great news! YOU CAN! The key to not having pissed off customers isn’t giving them what they think is fair, that changes daily, and from person to person. It's also not having the power to fix a problem after the fact, cause well, most employees have little control of the deal being made anyway. The key is, in fact, managing their expectations.
The corporation that you are a slave to wants to give people high expectations in order to lure business, but has its true interests in the bottom line (profiting as much as possible). It's called Bait and Switch, and it's pretty damn common. Basically, this creates a set up for you getting to deal with a bunch of disgruntled patrons who expected to get more than they did (or to pay less than they get billed for, or.... etc.). Corporations don’t care that this practice produces pissed off customers, because all the other big dogs do it too, and because YOU are the one who has to deal with their righteous indignation. (Oh, they might read a couple letters here and there from people who take the time, but YOU get the snot and insults to the face.)
The answer is FUCK CORPORATE and their bullshit policies. BE HONEST with your customers about what they can expect. Think they might get caught in an "extra charge" trap? TELL THEM! They clearly want more than the deal they think they are buying? SAY SOMETHING! Don't just stand there while they sign off on 6 pages of fine print no one takes the time to read telling yourself that the surprise will be their fault. Put in a little effort, and let them know what's up. They will be happier, and you will be the good guy.