I am currently on assignment in the middle of no where and need to tell the local mechanic what needs to be checked.

change engine oil and oil filter. inspect brake system,tires,tire pressure,exterior and interior lighting,windshield washer and wiperblades,reset maintance light,battery,coolant system,spare tire pressure,test sos emergency system

I believe that a service A is just a routine oil change along with the filter and a visual check of any fluids (even though the car will tell you if anything is low). I'm planning on buying a mercedes this summer and through my research on the car I've only come across Service A as an oil change mostly b/c many people like to do it themselves and want to know how to reset the computer in the car so it knows that it was changed. Good Luck