It is O.K. to have expectations because it is quite natural to have such expectations, but realise that having expectations is one thing, reality is another thing.
When a bad thing happens, learn not to be surprised. Because we have to deal with human beings who can be forgetful and we have also to deal with human beings who are not so responsible. We should be surprised only if we find someone who is perfect! But there are no people who never forget and are always responsible. We should remember that we are living in a world of imperfect human beings.
Another suggestion, which is very important, is that you must show that you are a cobra. But you must learn to play it like a game. You must say to yourself: Now I’m going to call this man who has forgotten to attend to this very important letter and I am going to speak to him very firmly, in a very tough way. You should know very well you only pretending; you are consciously doing it but inside you have no hatred towards him. Some people only understand such language. So you can state really firmly that next time you do such a thing I will reduce your salary!
Another interesting suggestion is to try to have a dialogue with that person. It’s a very interesting exercise just to raise questions in such a situation. Now tell me: What happened to you? Why did you forget? Is it because you were not really interested, or you had other more important things to remember? Are you normally forgetful? Just get him to reflect on what has happened. So it enables that person to reflect on his own actions. This can sometimes be extremely helpful and it can reveal to him something that he might not have looked at before.