Removal of air filter housing on ML-420CDI

Does anyone know how to remove the air filter housing on an ML-420CDI ? I had the filters out and removed the 2 bolts at front, but can't see what holds it at the back. I'm wanting to get to the hall sensor, which I believe is under this.

Also, anyone have an idea how I get the audio 20 out. I presume it's a case of pull the facia from around the ashtray and then I can get access to the retaining screws.

2008 W164 ML 420

Thanks in advance.