"It is going to the shop" You should take the car to an independent garage that deals only with European automobiles, a general automotive repair shop may not get you where you need to go and they will not have the experience with Mercedes systems. Your car will scan as a 2003 Mercedes SLK 320.

If you have anyone near you with a Crossfire I suggest you first take the RCM from the other car, place it in your car and go for a test drive. Your problems may all be related to a faulty coil on the RCM. Another possibility is the brake light switch. If you get a good scan into the Mercedes codes they will point you in the correct direction. After the car is scanned; CLEAR ALL THE CODES; go for a test drive and then scan again for any codes that are reset;. Those will be your problem.