I doubt you ever will but it would be nice to know some stats on that -
Assuming they are all 180's.
Are all 4 vans of a similar age (Chassis/Engine No.)?
Do they all have the same SW version of the ECU?
Are all 4 vans of a similar mileage?
Manual or Auto - All the same??
If they are not all California - What are they?
Is there a common link with fuel used?
Have all 4 vans been serviced in the main dealer network?
What oil has been used when servicing and topping up?
What parts of the UK are they in?
Why so many more in Germany, greater volume of sales or some other link?
I would suggest they have a word with Oli and get hold of a Cali for you if they can't source one themselves.