Sounds like you need to replace your ignition. I just replaced mine in a C280. On the C there is a cable that goes from the shifter and screws into the side/back of the ignition. Before fixing it I figured out that if I unscrewed the cable(ignition end) and pushed in the metal tip I was able to get the car out of park into drive etc.

There is a lock/switch in the ignition that is supposed to unlock your shifter, obviously this is not working properly and needs replacing. Your key not coming out of the ignition is another sign of a bad ignition.

You can write down your VIN number and order a new ignition that will match your old key from the dealer. As far as installation, its not for a beginner, takes a bit of know-how but It can be done 'shady tree machanic style' if you have the will and patience.

Another bit of advice, replace the ignition before your key wont go in the ignition at all OR will go in and not turn. Once this happens the job gets a little more tricky, and if you have a dealer do it at this point you might be looking at $700 plus bill to fix it.

Good luck,

-M