Again people, i don't want to hear your opinions, I need helpful advice, if you can't supply that, sorry to say but don't f*^$*# post!
The most helpful advice I can give you as someone fairly knowledgeable about the subject is that you simply don't have a chance of getting the decision overturned. Polish law is very...how to say - black and white. You broke the law, you were punished - end of story. Serve your time, get a visa when you intend to return and there should be no problems.
Ultimately, you broke the law and you've been let off lightly. They could quite easily have banned you for longer!