Hi RAB,
I haven't yet the file from the VCDS (but I will). In the mean time I have quite some news from the Audi garage. First of all, the potentiometers they replaced (the first time I took the car to them about 1 month ago) were, like you said, the ones near the gearbox selector lever. Nothing else was replaced (that's at least what they're saying now although that's clearly not what I understood before). According to them, no fault codes were detected neither then and neither now. I even asked for a copy of what they did exactly the first time (their report) and the answer was: we can't, Audi doesn't allow, there are procedures in the report which aren't public. I confronted, to no avail, the Audi garage to the fact that I paid 2000CHF and finally the problem was something else and that they didn't see it. They ask 180CHF/hour by the way (that's roughly 140GBP).
This time, they say that they found out the problem is that the clutch slave cylinder is leaking and also that one sensor (probably the 'clutch movement sender'?) coming from it indicates that the clutch wear has attained the limit. They said the clutch needs to be replaced as well as the clutch slave cylinder. They told me how much it would cost to fix and I said NO (>3000CHF: 9 hours work plus parts). The car is now back at home. RAB, your words about Audi garages were prophetic.
Again, whenever I turn off the ignition key and then retry to start, the clutch doesn't disengage. I asked them how they explain that. They said that maybe there's a safety feature: during driving the problem might show up but the "car control" won't stop anything until I stop and turn off the ignition key. The fault then stops me from restarting (but there aren't any fault codes...). Also that when I try to push/pull the car it somehow forces the slave cylinder to a "good" position or that it somehow "resets".
RAB, I can't move the car when I push/pull: it just kind of "shakes" back and forward (I feel the gear engaged).
What I did exactly today (back at home) is the following: with the ignition key turned on, I put the selector lever in neutral (it doesn't disengage! but the display panel indicates I should be in neutral) and try to push/pull the car and THEN I hear and feel the clutch disengaging. Since the hand-brake is off I then even feel the car being free to move (I should never do this is an inclined road!!!).
I'm hoping that only the clutch slave cylinder is faulty. Any advice? What would you do? Thank you very much.
Cheers,
Miguel