In my area, it's gotten to the point where folks are actually surprised when people treat them courteously.
I went to pick up a large food order from our local Chinese take-out place. I'd ordered online and I'd ordered some "extras" that didn't show up on the bill when I placed the order (extra sauce, noodles, etc). When I got to the place to pick up, the bill came up as different than what was on my order (by about $4.00), as I expected.
I said, "my online order was $xxx.xx, and this order is $yyy.yy, is it the right order? I want to make sure it's the right one."
The poor guy got embarrassed and tried to explain that I'd ordered the extra stuff and he adjusted the bill accordingly. I cheerfully told him that I fully understood about that. I just was making sure it was the right order and was just making sure there was no confused switching of orders or something like that, I surely wasn't arguing about the extra $4. I just wanted to make sure that when I got the order home, it was what I ordered and not another big order that might have been placed by someone else and gotten switched by mistake.
He looked like he was about to cry in relief that I wasn't arguing with him, screaming at him or being disrespectful.
I find that most of the time, even when there is a screw-up, confusion or a bad situation, anger, disrespect, nastiness and bad manners rarely help the situation.
Aqualung