Erratic turn signal operation can be a result of a failing turn signal flasher relay which will require replacement.Google+
Car Problem Reports
Volkswagen Beetle TDI Flasher Relay Failure Can Cause Erratic Turn Signal Operation
Volkswagen Beetle TDI Problem
Average Mileage: 72,000 mi (32,000 mi - 100,000 mi)
I had this problem too, but fixed it by spraying contact cleaner into the blinker stalk pivot area in the steering wheel column.
erratic turn signal flashing.
Visitor, 2005 Volkswagen Beetle TDI, 32,000 mi
Flasher relay is erratic when right signal turn is performed.
need to replace flasher...where did those clever germans put it???