Rear view mirror issue

Hiya,

My GF has just been totally shafted by a garage I fear.
The rear view mirror is supposed to be an automatic dimming one… The one in the car is stuck on with black silicone. The sensor thing is in the arm rest!
The model is Ds4 Elegance Bluehdi S/S Auto the wiring is all curled up in the plastic bit above the mirror and there’s a plug missing off some of the wires.
Does the proper rear view mirror clip onto the fitting the sensor fits into on them windscreen? And is it the same one as a Citroën C3 auto dimming one?

Hopefully photos have uploaded. As you can see they mullered the screen!