[330DW]

I see where you are coming from and if I were you I would be pretty fuming they are trying to wriggle out of a warranty claim now, after honouring other items through your ownership. If they hadn't dug up this service issue would you have even noticed, and is it that particular incident that has tarnished the car for you?

IMO, although option 1 or 2 are the ones that you may prefer it is probably going to be option 3 that is most likely. I imagine they might offer you a "settlement" along the lines of fixing the turbo issue and in addition for a good-will throw in a free service or additional warranty time.

Good luck with it and hope you get the result you want!