What is cost range to replace 2003 MB CL500 ignition switch at Florida dealer?

What is your question?

Car cut off twice when at stop lights. Tech said new alternator needed and was replaced. One month later the key will not turn in the ignition, no crank no nothing however lights and radio work. Dealer says ignition switch needs to be replaced but does not promise that the car will start or operate after this $2300+ and said other repairs may needed once car is operating and can be full examined.

What makes this problem better or worse?

nothing

How long has your 2003 Mercedes-Benz CL500 had this problem?

2 weeks for key not turning in the ignition; 2 months was first time the car cut of twice at traffic lights, after first not start in a parking lot.