Replying to So this girl "lost" my BMX bike...

Last summer I got a brand new Fit Inman 1 2012 and rode it to my friends house. It was night when I wanted to leave so I had to be picked up. My dad later came with a car that couldn't fit the bike it in so I left it in her garage. The next day I came back to see my bike was gone and the helmet was lying there on the ground. We later realized that it was most likely stolen by one of her older sisters friends. None of them budged and her rich parents (yes, there rich, they own TrCcity Bank) paid me off $250, $100 less then the bike cost. I mean come on your a fucking millionaire and you can't pay me $100 more... We just left it at that. So 2 weeks ago my friend calls me saying he found the bike and it was sitting in her older sisters car trunk. He also said it was customized, everything but the frame with the serial number on it. I have the paper work for it with the same serial number on it. So my dilemma is do I go over there and take it back throwing fists, call the police and easily get it back, but have them charged with thief, or just keep the $250 and not deal with it. Thanks NS