Dodgy clutch, any ideas?

[Road2Ruin]

Evening chaps,

Looking for a bit of technical expertise.
My Volvo XC60 has been showing a weird issue and I am at a loss to work it out.
About 6 months ago I took it on a long journey, about 250m, mostly motorways. Near the end I noticed the clutch pedal had gone soft and stuck to the floor. I also could not change gear. After pressing it a few times, it reverted back to normal. While driving around town, all is OK. On the return journey the same thing happened, but again depressing a few times makes it mostly better again. It's not losing any fluid, but must have some air in there I guess.
Any idea on what the fault could be?
It has an internal slave cylinder, so difficult to look at it without dismantling a lot of car.
Ta,
R2R

[Road2Ruin]

E-bmw said:

Age?

Mileage?

Engine?

2013, 100,000 miles, I believe its an old Ford engine in this model. 2.0 D4.

[Road2Ruin]

ozzuk said:

I have a 2014 plate XC60 but the D5, bought in Jan. Within a few weeks the clutch pedal stuck straight to floor - I could pull it back up. Dealer collected car and replaced the slave cylinder (I think) and also did the clutch (engine at 72k). Since I had it back it's twice stuck halfway since reversing but seems fine now.

I suspect it could be this, but it's an expensive job, especially as doing the clutch plates at the same time makes sense.
If I only drive mine round town, it's fine. Long journeys, it isn't. I dd bleed it a while back and it had loads of air in it.