It is possible to get the aux working on it again and with out buying a plug from audi. I have done it before. You will need to use vcds to code the radio to tell it it has aux then when you press the media button you should see aux or external media (something like that. You then need to remove the radion and remove the blue plug from the quadlock and that the remove the black cable holder from that blue plug and plug that into that big 32pin slot on the back of the radio. If I'm not mistaken you need it on pin 21,21 and six. It's a lot easier than sounds just plug it to the far right and it's done. Hope that make a bit of sense as I muddle up some times.
Let me know if you need help. I'll see if I can get a picture for you too as I done this on my girlfriends car