I took the seats out on my old w202 (four torx bolts) and used the stair attachment on my carpet cleaner one weekend. For the effort of taking them out they were much easier to work on just be careful of any wires under the seat which connect to the occupancy sensors. Once you disconnect them do not turn the key in the ignition as you may end up causing the air bag warning light to stay on and need switching off.
If you purchase any sprays or foams top tip is to cover you centre console with a large towel as they go everywhere.