Hi Nick,
I sympathise with your situation, I cannot begin to think how I would feel having spent a lot of money and not being satisfied with the car or the service. It just isn't good enough.
Dave W is being encouraging in asking you to give it time, but time won't make your car any cleaner nor will it make your past contacts with your dealership any different.
It is very interesting that some of the most popular topics on this forum are concerned with bad design and poor service. I wonder how many prospective buyers are put off, or does it matter when there is a queue of buyers.
I wish you luck and hope things start to get better for you.
Peter