X5 e53 Airbag light {dealer no error code & erratic communication}

Hi,

my x5 has the airbag light on the dash, I ran it into the dealer hoping I would get the error
code confirmation, and the fault rectified, day 1 in the garage involved the first level of
simple checks (50 quids worth) with no fault showing, the Beamer garage test
instruments i have been advised show an indication of communication intermittence -
something I have not even come across on the world wide web.

Day 2 in the big brother dealer involves lifting centre console and seeing if they can
identify the fault (under 300 notes£ worth) My concern is that this voyage of discover will
eclipse the value of the car. All of my research so far indicates that even faults with units
like the Airbag control module display fault codes

is it fair to say that I am paying for someones training schedule here - anyone come
across No fault, communication breaks, they cant talk to the airbag system units etc. I
mentioned could they not check replace the most common airbag units causing issues
such as side pasenger sensor, 'No' was the answer as the electronic unit we have
plugged in cannot communicate with these end units.

Is there a Brain system that handles the fault communications. Dubious because what i
have been told in the showroom I can not match on feedback on the web. Help... if its not
the centre console area then this could ramp up the costs like an out of control slot
machine