Replacing a windscreen wiper blade
Fold up the wiper arm when it is in service position. Service position is activated/deactivated via the function view in the centre display when the car is stationary and the windscreen wipers are not on.
Set the wiper blade in removal position by angling it out from the arm until a click sound can be heard.
Press and hold the lock button located on the wiper blade mounting and at the same time pull the blade straight out 
parallel with the wiper arm.Slide in the new wiper blade until the lock button engages.
Angle the blade in towards the arm until a click sound is heard. The blade is then no longer in the removal position and can be moved again.
Check that the wiper blade is firmly installed.
Fold the wiper arm back towards the windscreen.
Note
The wiper blades are different lengths. The blade on the driver's side is longer than on the passenger side.