Will it go in and out, just not turn, or is it totally stuck? Can you maybe try to put some lubricant on it to help slide things along? I would definately take it to the dealership asap. Either drive it or tow it. Try to turn it upsidedown and reinsert it. If it won't come out and it won't budge, I'm afraid that I'm out of ideas. The dealership is my best advice. I'd be reluctant to take it to an independent, but that's just me. That has sometimes cost me more in the long run that the dealership would have. Anyway, sorry I can't be of any more help.
Good Luck.

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Kyle De Priest
2007 e320 Bluetec
2013 GLK 250 Bluetec