I have the same problem with my front passenger side window and I am going to have a go at fixing it myself with brake cable.
Just to let people know I also had a problem with my rear window, which was a completely different mechanism, and I have managed to locate the fault. This regulator has one rail and a large cable with wire wrapped around the outside like a screw. This wire goes through the rail and attaches to the plastic clip that the window fastens to. The problem I have is that the cable has broken off the plastic clip (plastic clip snapped). Hopefully I can buy a new clip from the dealers tomorrow and that should fix it. If not it could be a long day stripping doors at the scrap yard for me tomorrow.
Thanks for all the advice and help from fellow Renault owners on this forum. I hope my situation is useful to others of you in the same boat.
I know the clips you speak off are available for the Scenic II not sure about the Laguna tho ?
Click on the link below for details
Renault - Scenic II - Window Regulator Brackets/Clips