Customer's 2010 c300 steering won't unlock
 

I don't have much more than that to go on. Is there an issue with the car's lock?

Key goes in and turns, but will not unlock the wheel.

Dash says "take your key from ignition" when key is inserted... No spare key... Dealer wants to replace the lock interface..
Help.
Guy is stranded in dealer lot.

see this
Car won't start Steering wheel lock? - Mercedes-Benz Forum

yeah common problem with the 204, its going to need a new EIS. remove the steering column, cut off the old eis, install new one and install column in car. using the blue workshop key to program new EIS and then initial start up wil have to be performed using a SDS.