the customer is always right

I wish someone would try to prove to me that the customer is always right. Let me tell you something, they are rarely right about things. Now, that's not entirely they're fault because what it boils down to is no customer knows store policies like an employee. Let me give you an example. I was working at the custmer service desk yesterday and a gentleman came up with a rebate check from corporate. He asked me if I could cash it for him but my manager informed me that we cannot do that in our store. So I kindly told the man this and he just could not accept that. He started to go on and on about how ridiculous it was that I wouldn't cash a check that my company wrote. Now, I have learned over time to not totally be a smart ass with customers because that gets you in trouble. However, it is not my problem that you work until six pm and could not make it to the bank to cash your check. Nor is it my problem that corporate wrote you a check that I can't cash at the store. The thing is though when someone is continually rude with me I can't help but return the favor. So every time this man repeated himself I would respond, "I'm sorry sir there's nothing I can do". He didn't like this and walked away. Later he tried to pay for his items with the same rebate check and proceeded to tell the cashier how ridiculous it was that we wouldn't accept it. What's the moral of the story? As a customer we should never assume that we know more than employees, especially managers that have been with the company for years. There are times when the customer is right, but when you're wrong about something just accept it a move on. There's no need to cause a scene. Most of the time if you are polite and patient with the employee they will do all they can to help you.