[JayG]

If the insurance company totals it, they not will have to pay to replace your Boxster, they will have to pay for the repairs that have been done.

I would first talk to the adjuster and if that doesn't get it resolved, speak with their manager and keep going up the food chain until you get it resolved. They probably don't have your car valued properly anyway. Remind them of the true market value based on your upgrades

I really don't think they will want to effectively pay double the car value.

Sounds like the repair place screwed up with the lights and is trying to cover extra costs