Perhaps the other person doesn't realize that you are feeling unsatisfied. Relaxation methods such as deep breathing may help to calm you down. When you feel yourself getting angry, stop, remove yourself from the situation and take slow deep breaths until you feel a calm returning. Try yoga or meditation to help you get in touch with your feelings and release pent up feelings. Think before you act.
Angry people tend to react quickly to a situation, which usually leads to an over reaction.
If you are in a heated discussion or you feel yourself getting angry, stop. Don't say the first thing that comes to mind, think carefully about what you want to say. Think first, then speak. Change the way you think. This may be easier said than done, and it will take some practice.