I agree. DIY and do it right.
I did C320 for the first time a few months ago. About 5k on the odo. Rhino ramps and less than 1 hour, start to finish. The hardest part was removing the plastic covers from the underside and that just wasn't that difficult. The rest is oil change 101. Pieco-o-cake and I know I got ALL the oil out since I poured abot 1/4 quart of new to flush out the bottom of the pan. I waited 10 minutes for it to drain. :-)
Two minutes is not near long enough. That and the fact that they are the King of the drain plug thread strippers is why I don't take it to them.
You are much better off changing it at home regardless of your method as long as you change it frequently enough.
Have a great day,
Change oil hot and change oil often.