Overfilling the crankcase causes the main crankshaft bearings to become partly submerged in oil. As the crank rotates, it causes the oil to cavitate (fancy word for a kind of bubbling). Well, anyone who owns a boat knows that cavitation of a liquid wrecks things FAST. Good way to wreck a prop.
Your main seals will be shot in no time. You're looking at $1000, maybe more to do both. My dealer overfilled my crankcase on the C230, and I didn't check the oil for a few tankfuls. Both of my main seals were shot, and the dealer acknowledged their error (unusual in MB land) and replaced both seals with no charge to me.
Drain some off, or use a LiquiVac/Topsider. Don't drive the car this way.
1998 C230 "Black Betty"