Some Benz models require the back seat to be removed, your could be in that catagory!
From MB: Loosen shocks only when vehicle is on the ground. On SL models with
removable top, remove top and open storage flap'
On all models, remove rear seat and backrest. On SL models, remove locking lever
from top flap and unscrew lining. On all other models, remove nut and rubber ring of
upper shock mount. Remove lower shock mount from semi-trailing arm. Remove shock in a
downward direction. Install is the reverse of this proceedure.