Mine went bang on Saturday.
Spoke to them this morning and they quoted £4500.
I explained that as the car had a full service history from them and that I had asked for the camchain to be checked 6 months ago (fortunately my brother-in-law worked for them at that time, so I threw his name in as a witness). I informed them that I expected them to cover the cost regardless of it being outside warranty.
It got interesting at this point because they had apparently recorded the last three services as the same mileage. By the time I got down there with my paperwork, all geared up for a row, they had spoken to vauxhall who have offered 90%.
Once I'd given the guy his arm back, he said theyr'e just waiting for the engineer to come out and authorise the repairs.
It was easier than I was expecting which makes me think someone cocked up somewhere and they're doing a hasty cover-up.