Went to my dealer today to ask how much it would cost to activate a second hand sat nav SD card (that I've seen on an internet auction site...). I was advised by the service guy that these cards are issued with one compatible activation code and that once that code has been used once, it can't be used again!.. Now, I am by nature fairly cynical and wonder if this is actually true, but knowing how keenly manufacturers try to protect their investment from 'spurious abuse' it might also be true. He also said that only Audi can reset the service warning indicator and they've had irate customers who've had their cars serviced outside the franchised network and then try to get the dealer to reset it only to be gold Audi won't do it unless they perform the service... Hmmmm... Incidentally they offered me a new satnav SD card for 185 quids and free activation!..