I had this problem when I bought my 2004 3.2 hope fully someone might find this helpful
if you move your seat in to the fully up position using the handle on the side of your seat and then move your seat fully forward using the handle at the front. now if you look under your seat you will see a cable about 6-8" in length there is a plastic clip which should be attached to you seat this breaks and comes loose from the seat so when you tilt your seat forward the cable doesn’t have the pivot point to fully complete the movement of the component on the runner to allow the seat to slide forward and back.
trim on the back of the seat
here is the cable and you can see the broken part of the clip we are replacing
and the slide component on the runner in the locked position (will not slide)
and unlocked position (will slide)
i undone this part of the cable on the slide component as you need the seat in the tilt position to do the work and this just makes the cable slack and easier to work with. When taking the cable out you need to be careful with the locking part that connects to the clip.
And also the threaded part at the other end that has the yellow mark on it.
These can and will break if you are to ruff with it.
I used 2 cable ties to keep them in place so it wouldn’t happen again temp repair when I bought the car.
you can just see the plastic clip in the picture all I done was wrapped a cable tie around where the clip is to hold it in place and then put a cable tie up and down the way to hold the other cable tie in place as where the clip goes is rounded so the first cable tie tends to slip off and the clip will break off again ( you will not see the cable ties once you put the trim back on)
That was the temp repair I carried out now I have replaced the clip.
i phoned Stirling Audi to get a price for the clips that have broke. The clips are under a £1 , i didn't think they would sell just the clips but they do.
Part number 2004/2007 a3 Quattro 3door
1k0 881 132B passenger side
1k0 881 132C drivers side
But please check with the dealer before ordering.