Poor ride advice needed E500 Coupe

I am in Uk and 3 weeks into owning a 2011 E500 coupe. (5.5L M273) Previously I had an e350 CGI SE coupe which I loved.
The new car rides so poorly I wish I still had the old one...
It has the sport suspension with the sport button on the dash. This makes a very obvious difference to the engine electronics and transmission but no discernible difference to the ride.
I am on 18" staggered oem amg wheels, 2 year old Sportcontact 5P tyres with plenty left. The ride improved quite a bit after 50 miles so i am guessing they had flatspotted a-bit.
I have had the wheels balanced, 4 wheel alignment has been done. I have taken it my MB indy who says all the bushes are fine, it has passed 2 mots in 6 months no advisories...
I am used to a feeling of stateliness and grandeur from 6 years in the E350. (non sport suspension, 17" wheels, touring tyres)
This car however does not make me smile...
It crashes over the smallest irregularity. The car body feels like it is shimmyinng on top of the wheels. I am so shaken by the car over irregularities / edges /potholes that my shaking feeds back into the steering wheel... It is only composed on perfect surfaces.
I asked the indy to check the rear subframe and do a test drive. The subframe was 'poor' but not unsafe and wouldn't get changed by MB. The test drive report was 'he didn't like the drive' but with no suggestions as to what to do...
I bought this as an 'upgrade' but i feel I have lost a great car and replaced it with a nail.
I could easily put touring tyres on. I could fit smaller wheels and add touring tyres - however i feel that it could not possibly have been made like this -different wheels /tyres would be just
a sticking plaster... so there is something else wrong...
Front springs were done 2 years ago. Car has a full MB dealer history. Motor mounts are oK...
Do I just assume the whole suspension is shot after 15years and 74kmiles and change everything..?
I am at my wits end and concerned about putting 2-3 thousand into new struts and springs / associated mountings to find it still drives like a clapped out AUDI A2...
Any thoughts most welcome...






