Quick update

I took the car to the stealership on Saturday, they fiddled around with the car for 2 hours and could not determine the fault. The guy working on the car said he kept resetting a fault code, something to do with a failure to engage ESP, but no matter how many times he reset it, it came back up.

They said I need to book it in to spend some time with their specialist electrician at £130 per hour! He's on holiday for 2 weeks, so will wait till then. At least they didn't charge me anything on Saturday.