Hi all, sorry to take so long to update life got crazy. It turned out to be the Electrical Harness. A seal had cracked and let some moisture in. All in all, cost £34.38 for the new part and £429 for labour. stick on VAT and £556.06 in total. It's not fun, but looking at some of the prices, I'm glad it was only in the hundreds, not thousands. plus I did have 3 coffees and 4 cookies in the lounge so almost made my money back 
Would be nice if independent garages could work on our cars as I think the labour charge would then start dropping.
Would be nice if independent garages could work on our cars as I think the labour charge would then start dropping.