Thanks for the replies guys.
Jimble - I have read through your thread. At least it seems the dealership have been very helpful and managed to come to an agreement you are both happy with relatively quickly.
I think there is some confusion here, i will try and clear that up. - The rear bumper has always been a different shade of white to the rest of the car. I fully understand that manufactures struggle to get an exact match and some discrepancies are acceptable. However this rear bumper is a completely different shade of white, it completely stands out from every rear angle of the car and is really noticeable in the sunlight. In contrast, the front bumper is a perfect match. See picture (also shows one of the chips).

The issue with the repair job is that the paint use does not match the original "pure white" it looks like the white that was used on the mk5 and mk6. You can clearly see the differences in paint shade in the below picture. Take a look at the door handle and the area next to the rear bumper, below the rear light cluster.

Neither of these pictures have any photoshop applied to them. They are straight from my iPhone, if that can pick up differences then the human eye certainly can.
J