Office chairs delivery

I work in a delivery service and I basically am a courier. I like my job because, frankly, I like driving cars. I drive a lorry each day and deliver different kind of packages to client from all around the place. It gets pretty annoying at times, especially when the clients who have ordered something are rude to me and this takes place pretty often. I do not know what it is about is that makes us think that we can say and do whatever we like. I mean, we tend to be very rude towards each other as of late. I work in this delivery service for over five years and I have noticed the change in people"s behavior about two years ago. We have changed our attitudes drastically. Of course, I always try to stay calm because, quite frankly, I cannot say or do anything to offend the client as I would lose my position instantly. I have to keep a poker face going. Yesterday I was delivering two Office chairs to some businessman. This guy"s behavior towards me was disgusting. As a matter of fact, at one point I wanted to tell him what I thought of him but I refused to do so, fortunately. Although he has ordered those Office chairs, he did not want take them. He said it was my mistake that I brought them to him.