The idea of Karma is not for you to seek revenge but to grow through the lesson and move out of that particular wheel of karma. Sometimes it takes for things to happen again and again in order for us to see the lesson. Usually it is a common occurrence, and is often reflected in the way others treat us. The key is to look at that, and then look at your own reactions to this. The power is in choosing to react differently and in a way that will initiate positive change for yourself.
In doing so the people that you interact with are then also given the power of choice to either continue on treating you and others the way they always have (and many do choose this), or to make a positive change for themselves.
The cogs in the wheels of karma keep on turning and as we grow we in turn become more enlightened, then we move onto the next lesson which brings with it its own karma. As we progress forward and learn, the intensity of your lesson will reduce and your higher awareness becomes your thought processes in the most natural way. This is when you merge with the higher flow of existence.