Hi Bustanut,
We finally got the AMI going -
Enable Media Player 3 in the CAN Gateway, then go into Module 56 (Radio) and go to Byte 11 within the long coding helper .. In that byte there will be a bit which is called Multi Device Interface (MDI) settings active. Tick this, close VCDS and lock the doors using the key.
Wait a few minutes, turn the car on and now select AMI from the source menu in the Radio.
Parts were from Audi but I'm not sure how much they were as the unit was installed beforehand.
What threw me off was, that I was looking for Audi Music Interface, not Multi Device Interface so once that was ticked, the whole system worked.