Ok well to wrap this up, I got the car back this morning (albeit in a complete dirty mess state with marks where they removed the windscreen, plastic cap missing from the front bumper etc) and the description was:
'Rectify leak from OS 'A' piller. Replace main ECU.'
It took them over 3 weeks to identify, fix and give me my car back.
One quick question, if they replace the ECU, would it send all settings back to default? ie. Mobile phone pairing etc?
Only reason I ask, the car system seems to have all the same settings and my phone is still installed on it.
I know nothing about car compueter systems but would have thought this would have been the case.
Hey ho...