Well either I'm stupid or Audi shoud have thought this out better.
The rear seat belt buckles for the 3 point belts on my 52 plate A4 seem fixed and recessed flush with the seat which is great until my wife tried to fasten the belt on our 5 year olds new booster seat. The fact that you can hardly see what your doing (have seat for our 2 year old on other side) doesn't help, plus we have a fitted waterproof cover to keep the seats nice and clean. I tried to pull the buckle out further to no avail and manual didn't help.
So I ended up buy one of these of eBay http://cgi.ebay.co.uk/ws/eBayISAPI.d..._promot_widget
the type X fits perfectly and now my daughter can even fasten her own belt!
Would recommend to anyone (and no it's not me, a friend or relative selling them) unless of course I'm just being stupid and they pull out further.