Paging the cage air-conisti

I have got a BMW cage that leaks all of its gas out in a matter of days.
When I had it re-gassed for the first time this year, the guy that did
it noticed that the condensor (auxiliary) fan wasn't working. He thought
it wouldn't be a problem unless I was stationary for long periods of

From the little I know about aircon systems, I believe it won't work very
well at all without the fan running - normal airflow due to the car's
movement just isn't enough. Shouldn't damage the system though - there
should be over / under pressure cutoffs to protect it.

Yes that's definitely the case. In the brief period it was all working,
it was much cooler than without the fan, even at high-ish motorway speeds.

time. A couple of weeks later all the gas was gone. So, I fixed the fan,
had it re-gassed again, and he also bunged in some leak-fixer stuff.
That was four days ago. All the gas has gone again.

Both times he has vacuum and pressure tested the system, and there are
no obvious leaks. (Second time around, under pressure test, we thought
the pressure was dropping -ever- so slightly, but it was really hard to
tell.) Both times he has also added the fluorescent leak indicator stuff
- but there is no sign of any leak.

How can I find out where it's leaking? Can anyone recommend someone that
might be able to fix it, Newbury/Berks area?

Or similar.

Spray on when the system is under pressure.