If I understand you correctly, you changed the ball joint. Did you replace one side or both? It seems obvious to me that after you changed the ball joint, a severe vibration resulted.
I'd recheck your work to see that every suspension component is attached correctly and that the ball-joint is also correctly installed.
If you didn't do it, take it back to the shop immediately.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".