CLS (in)stability at speed
 

My 2007 CLS 500 (388bhp 5.5l) feels unstable at motorway speeds - it feels unsettled as though it is rocking from side to side. This situation applies with the active suspension set at the ("hardest") setting II.
I mentioned this to my local Mercedes dealer when the car was in for a service, and they road tested the car on a motorway. They too noted the feeling. They then road tested another CLS and noted the same feeling and concluded that everything must be okay! I spoke to Mercedes UK customer services, who reported back that there is nothing to be done, because it is (obviously) typical with the model!
I exploded at this point - this is a car that, even with the UK speed limiter, is advertised as capable of 155mph! I for one would feel totally uncomfortable to drive the car at anything like those speeds (speed limits permitting) when the car feels so unstable.
Does anybody else have similar concerns with their CLS?