Wrong!! the bulbs can be replaced. There are 2 different brands of pushbuttons, so the bulbs are accesible in different ways. On the Bosch brand they can be removed w/o removing the unit, on the Kammer brand the unit must be removed. Find a dealer or ind repair shop that knows something about the car.
MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. TECH
190E 2.3 ITS RACECAR