Clutch pedal stays down intermittently

[travis32]

Hi, I have a 2016 Leon FR which had the clutch slave cylinder replaced last summer, a few months later the clutch pedal stayed down, I pulled it back up and drove off, my local garage, where I had the cylinder replaced, checked the car over to see if there was a problem, they said it was Ok. It's been fine up until today, where it's happened again, fluid level is fine. Any ideas why this intermittent fault happens. Thanks. Paul.