Engine Knocking Noise problems of the 2006 Volkswagen Passat

I've had my 06 Passat for little under 2 years now, it was bought used from carmax and it has been horrible from the start. As other consumers have noticed I have a big problem with the key getting stuck in the ignition to the point that I have to start and stop the car at least five or more times before it will dislodge. Also, if the key isn't stuck the engine itself won't crank, also taking at least five tries before the engine will start. I have to take the car to a dealership regularly, about once every two to three months, fixing the same problems repeatedly. The check engine light is constantly on and no matter how many times I change the headlights they never last. My most recent problem has been the noises my car is making. It's like a rattling, knocking noise that has only gotten louder since taking it to the shop. The mechanic has said it would take around 3 to 4 thousand dollars to fix, which is only a small amount less than I've put into buying the car, not including the money I've been pouring into constant repairs. This is a horrible car and now that I've done some research and seen just how many other people have had the same problems I have (and more severe, potentially deadly problems in some cases) I make it my business to make sure everyone knows what a dud this car is and how vw does not care about its consumers by not doing anything to fix these ever prevalent problems.