Parts arrived!
From reading about the place, some folks seem to mention using code 15 at byte 18 for newer models. Mine manufactured Feb '10, so wonder if I need to use 15 instead of 4. Oh well, one way to find out!!
Edit: Seems using 15 might make the inner lights light up under braking too...
Mine is a Feb/March car and I too had problems with VCDS and coding.
I got round it by copying the long coding, changing the relevant values (oo to 04) and saving.
It worked fine that way - but the long coding helper wouldn't work.
Incidentally, here's an odd thing:
Std Xenons + lights in 'auto' + dayight = front Xenons on and rear lights on all the time as DRLs.
Std Xenons + LED rears (Byte 18 set to 04) + lights in 'auto' + daylight = front Xenons and no rear lights...
Turn the lights to either sidelights or main lights and the rears come on.
Odd...but better!
I never understood why the rear lights were on as DRLs.