I AM ON THE ISLE OF WIGHT SO GETTING THE SEATS REDONE IS NOT THAT EASY . I WAS HOPING TO GET A STRAIGHT SWAP WITH THE SEATS . THE S211 THAT I OWN IS ONE OF THE BEST DRIVING CARS I HAVE OWNED SO AM KEEPING IT LONG TERM .
Yes, I could see that: I'm a regular renter at Seaview, now that Priory Bay's closed down, and a fan of Lily's cafe. That's why I suggested Surrey Trimmers which are an hour north of Portsmouth, but there will be trimmers on the Island, or nearby.
S212 or W218 seats will be in a different leather and a different colour, and "may" have different cabling for the electrics, airbags and related SRS sensors. They'll cost in excess of £500 to buy from EBay, and probably as much again to fit - "if" they can be fitted, which is unclear. You'll also face issues around the different mechanism specs involved (full electric / half electric / oath / ventilated etc).
Even if they were same colour & leather, there would still be colour variation from the pattern of usage and storage. Some 15 year old seats are immaculate and look as new. Others: not so much.
As is regularly discussed on here, "some say" the S212 seats aren't as comfortable as the S211's, "all we know" is that you're happy with the comfort of your S211, it's an odd decision to throw away whole seats and switch models when the leather can be invisibly repaired, and renovated, for much less.
Here's a recent thread on seat comfort:
S212 comfort | General Discussion