Replace or repair damaged door trim - F31 touring

[woogeroo]

I picked up a used 2014 BMW 3 series at the weekend, and on the drive home noticed a few interior scuffs and dings that I'd somehow missed during the test drive.

They're on the front passenger door: just below the window, on the armrest.
https://imgrpost.com/image/oUEzU
https://imgrpost.com/image/oUuFN

And on the left rear passenger door: just below the window.
https://imgrpost.com/image/oUnI6

They're minor in the scheme of things but niggly and annoying.
Can someone recommend a sane (hopefully cost effective) way to get these replaced with new parts, or otherwise fixed?

Main BMW dealer or an independent BMW specialist?

I'm in Hertfordshire btw, if anyone wants to recommend a specific garage.