2014 Yeti Outdoor Suspension problems

Hi there.

Ive just bought a 11/14 Yeti Outdoor 4x4 and have some concerns about the suspension, specifically the rear shocks.
On test drive I noticed the rear seemed unstable over dips and asked the dealership for a check before purchase. All ok according to them, in hindsight I don't they looked hard to sell me the car and told me what I thought was leakage from the shock was overspray from detailing??
Since then Ive done another 2000km and the problem is still there. At 100kph on secondary country roads with their dips, bumps and potholes the rear shocks seem lacking in rebound. The vehicle goes into the dip ok, no jarring no bottoming out but then pogos out of it quite violently. On bends I can end up half a metre across the road with a mid corner dip.
The vehicle has a tow bar and electric brakes so Ive assumed its towed a load >750kgs previously.
Ive taken the vehicle to my local Skoda dealer and they checked it out on their computerised system with these results.

Left front Wt 468kg Shock 71%
Right front Wt 513kg Shock 76%