I don't have access to manuals for that model but if it is the usual hydraulic clutch did you check the fluid level?
As to going quickly, yes. One day it works and the next some seal is blown out. It can leak internally so no fluid would be on the ground.
https://www.google.com/search?q=hydraulic+clutch+working+animation gives you an overview of how this works.
My thought is not the clutch itself but either the master or slave cylinder at fault.
This is for a 06 Grand Scenic, Diesel, 1.6l, manual.
Have had car for about 4 years with no clutch issues until now.
Yesterday, suddenly, clutch pedal intermittently became floppy and started staying at the floor (when car was cold and warm). I was able to 'pull' clutch pedal up with toes and it became more usable for a while and then end up back at the floor. Now, today, it is worse and needed RAC call out to tow. The dash was bleeping up with 'STOP'/'Braking Fault'. I can't engage gears at all now. RAC towed me but wasn't sure what it was specifically.
A couple of times, as it has an electronic handbrake, it was struggling to pull away/disengage the brake.
The RAC guy says it *could* be a worn clutch and cost between 400-700, but can they really go that quickly? Garage I phoned said it could be slave cylinder, which they said would cost £1000+. I couldn't see any patches of fluid on the floor at home where it's stayed for a few hours.
Any ideas? I'll keep this thread going after I've got it diagnosed and fixed but we're trying to work out where to get it towed to and if it's worth it.
By the way, when you lift the pedal up and press back on it, you do have some resistance but after repeated/prolonged use it ends up going back to the floor, which is why I think the RAC mechanic suggested it could be the clutch instead of hydraulics?