I called Audi this morning. They quoted me £1600 for a new part. I then tried a couple of local garages, only one could help, but again it would have to be a new part as the VAG system flags up if you try to recode an old part - so they quoted me £1400.
As a shot in the dark, I have just bought a new cluster from ebay to be sent to ECUTesting to see if they can copy the code over from my dead one - they told me that they could at least talk to it, so there is a little bit of hope there.
With the OBD, I couldn't get anything out of the instrument cluster at all - when I clicked it in the app on my phone, it just popped up a message saying it couldn't communicate.