Gave the interior a vacuum and dust yesterday and today a good wash. Wasn't as dirty as I thought but certainly looks much better now:
The dealer had fitted a bumper protection plate to the rear which has been getting on my nerves as it was trapping seemingly enough water to float a battleship. Found out why today, it came off and upon examination I noticed a lip at the rear edge which is supposed to sit over the drop of the bumper whereas the dealer had fitted it too far forward. So it had never been sitting flat. Numpties. And they have fitted my rear number plate wonky. God knows what they are capable of given a real problem to solve...