C220 CDi 7g Tronic plus Viberation/shudder

Hi I have a 13 plate w204 c220 cdi with the 7g tronic plus gearbox,
the problem im having is if im driving along in eco mode at 50-60 mph and decide to pick up the speed I get a viberation / shudder almost feels like a manual car in the wrong gear, this will stay present for a moment till it gets up past 65mph

If I drive in S mode theres no shudder viberation at all!!

If I drive in manual mode at 50 -60mph in 5th gear and select 6th gear the vibration comes back into the car until it reaches a higher speed,

I've had 2 people look at the car and both diagnose as something different which leaves me confused,

Any ideas?