First your dimple dents. Unforunately the dealer is correct, You will have to live with these. The skin on an Eriba is very thin and marks easily, but on a dimpled van these marks show up less than a smooth silver.
As regards dirty waste trim, this will clean up. This has been covered in detail if you use the forum search facility, but basically try a rag dampened with white spirit or meths. One of these will lift the worst off, then follow with a good wash and possibly some window cleaner. Be aware of chemicals or rubbing to hard as you could easily remove paintwork.

Colin

This may be of interest: Brown Smeg

I was sold that story, and it's true. I carry a bottle of the stuff and supermarket antihistamine/hay fever tablets for midges.

Colin

I should have said for incase the midges bite me.

Colin