I've upgraded my headunit to an aftermarket item and no longer need the Xcarlink adapter.
It's been used for about a month, works as it should and all the relevant parts are included.
The unit has the additional bluetooth adaptor for handsfree calling and also the 3.5mm jack input, so it cost £127 new.
More information here: Audi iPod Interface�::�AUDI�::�XCarLink
£80 (postage free)