YorkshireBloke - appreciate the words of caution, this garage has replaced gearbox oil on my previous Allroad 2.7TT and B7 A4 3.2, all good so far - they're VAG specialists in the truest sense!
Snaggle57 - so true about V6 lumps ejaculating oil like it's in fashion. Gets quite tedious though, and I found evidence of sealant around the nearside gasket so I think a bodge has been performed in the past. I too expect it's the breather pipe playing up - would be an inexpensive and easy fix for sure!
I'll let you know how I get on