Gareth,
You are correct, the last time I checked the coolant levels was before Christmas and it was at the normal level. When I opened the bonnet yesterday it was at practically zero (about 2-3mm in the storage tank), due to it being night time I didn't see the puddle in the engine bay, only noticed this morning after I had topped it up with more coolant.
As stated in the earlier post, this does seem to be a very recent issue (within the last fortnight) and so long as my warranty covers the repairs I'm otherwise happy!
I also drive an A3 and have also noticed a few owners of S3's from the same period that my car was built have reported similar problems. Coincidence?
Thanks
Craig