I used to work in customer services for a major german motor manufacturer.
The advice I would give you, is to get in contact with customer services for the factory, explain your gripe with the dealers, explain you are not happy with the workmanship and insist on a new vehicle as it is not living up to your expectations and the core values that land rover stand for!
Give this a go. I frequently used to come accross sub standard dealers, if they get pressure from the factory, they usually s**t themselves and get your work done.
Hope this helps
jim