Yes, this happened on my S3.
The fluid in the pipe between the clutch slave cylinder and clutch master cylinder goes off and the pedal gets very heavy.
If you put a section of thin pipe over the bleed nipple near the gear box into a container, loosen the nipple and pump the clutch gently a few times you will notice the fluid is like treacle very dark and thick, keep pumping the clutch until the consistency of the fluid coming out changes to a thinner more yellow brake fluid.
The whole time you are doing this keep the reservoir topped up with fresh brake fluid.
I did that and my clutch went from stupidly heavy to much lighter to press and it made the car feel like a much younger car to drive.