devise not wirelessly charging in mercedes

If your iPhone has a cover on, try removing it. It has been seen before that the cover is too thick to absorb wireless charging. It may be redundant, but also make sure to place your iPhone correctly in your car's wireless charger pad.

Also try with another iPhone, or another mobile phone that supports wireless charging, in order to find out if it is your iPhone or your car's qi wireless charger that has the problem.

In the latter case, you must contact your Mercedes workshop.

You can find more information about wireless charging here:

How to wirelessly charge your iPhone - Apple Support