Sorry to get your hopes up. I thought that your car also had the free maintenance.
If you plan on keeping your car for a long time and many miles, and you should, change oil hot and often, even if you don't do anything else in the way of preventive maintenance. Don't get me wrong, I still encourage complete preventive maintenance. Maybe you can find a good independent shop to cut the cost of this. There are some independent shops that are better than your dealer for service. Check out the MB shops forum here.
Best of luck,
Change oil hot and change oil often,
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in