Hi all,
Sorry for late replaying but I was away for some vacation.

Well... first of all, a big thank goes to Stringbag for his kind offer.
Too bad I live quite far away from him as would have been really nice to meet in person.
Maybe I'd buy his TCU anyway, but I need to investigate my problem a bit more in depth because I was told thare is a wiring under the central armrest which fails quite easily due to the bending caused by opening and closing the armrest top over the years.
Too bad you need to completely remove the center console to reach and check it.

About Navcoder, it shows that there are NO errors stored in my TCU memory...

About the sim slot which is on the TCU, I dont know for sure if you can use it as a substitute for the one which is on the eject box, but it looks like that ...or better, I was told so.
It may be the one needed for BMW telematic services so, it worths a try... but it did NOT work in my case and the phone system kept asking for a sim card.

Big bob, the sim slot on the TCU needs an adapter to hold the sim card.
You may use the very same one that's in your ejectbox (number 5 here)... just need to get corners cut or it will not fit entirely in.

If you need pictures, I may get a few taken and posted for you... just ask

I'll keep you all posted about where the wiring check will lead me, in the hope that this post will be usefull for others as well...