Some of th guys on here specialise in breaking down lagunas, funnily enough i had the same issue. just see if you have a local renault breakers yard, they will do all the work for you, saves you heading off round a scrap yard will a hammer. I picked one up for £20. Easy to fit, but mine had two errors, the solenoid had stopped working and also the white arm that recoils the lock bar had gone, but my mechanic fixed that with a simple spring.
If you have the same reg car as me, i have to ask do you have leak problems.