That is useful feedback. In relation to the lights vs tailgate question, good point and it does seem to be the tailgate that is out because the lights align with the other panels whereas the tailgate is out of line with lights and the other panels.
Name and shame: in case I have to go legal with them, I want to avoid an own goal by naming them at this stage.
I looked around their entire car park / showroom and I didnt see a single tailgate like this so the 'factory specs' line doesnt wash with me. Let's see how well they fix it when the vehicle goes back in to them. Thanks to all for sharing your thoughts.