Madame Marissa was fired for a mistake she had not committed and she did not take it lightly. She did not want to go to court but she knew she had to get her job back. And that is why she chose to slap the shit out of her boss to make him come to his senses. She also had him know that she was not the one who had made the mistake. The faceslapping and ballbusting was to make him investigate things better next time.