R56 2007 Radio/CD/Aux with Sat Nav Screen
 

R56 2007 with Sat Nav Screen
The DVD gave up years ago but now the output from the Radio/CD/Aux has stopped with no sound.
Randomly it occasionally works but most of the time not. The controls all still work as the screen shows them but no sound.
I have read about separate amplifiers but the space where they are supposed to be is empty. I have checked all the connectors etc.
I even looked at replacing it but is seems there are only after market replacements for the ones without the sat nav screens and i would lose the reversing radar &B car data menus.
Has anyone got the audio configuration and wiring diagrams?
Or any help please?