I had similar experiences with my car, so I start doing some maintenance myself. I bought the factory service books for my car ('86 300E) and, I know the work is done with attention to detail. Not to mention the money that I am saving and enjoying every minute of it. Your car may not have the factory books or the new factory CD (call 1-800-for merc) since it is so new...
As far as the oil change, I have been using the "topsider" (there are different brands), around $50, which is a basically a suction pump looks like a small gas container found in most boat supplies dealers.
You warm up the car for 5 minutes so that the oil is warm, loosen the oil filter, stick the suction hose in the dipstick hole and let the "topsider" do the job for you. Once all the oil is in the "topsider", change your filter, fill the engine with oil and you are done.
No crawling under your car, everything is done from the top, no mess either. I am just a satisfied user.