The process at VW seems to be that the owner of the car has to turn up in person at a dealer with photo ID and the VIN of the car the stereo came off.
For best results, the car needs to be 'in their database' meaning the car the stereo came off must have been serviced at that dealer, or was purchased from that dealer.
If not, they have to login to the VW world wide network to retrieve the code from their databases in Germany. Seems to be a bit of a pain in the arse and may cause some liability issues for the dealer and they're hesitant to do that free of charge at most places.
Luckily, not every employee who answers the phone is 1. Familiar with the process or 2. Could give a damn about it. There's a chance that if you're nice enough, they'll just give it to you over the phone if you have the VIN.
I can reset the code on rns510 radios if they are lost. If they are bought from overseas, they sometimes have the number on the lid. I can do a couple of other tweaks to the radio as well. I invested a wad of money to do this on the side for legitimate people. Changing the number can make it easier to remember as well. PS I can also copy music from the hard drive to an SD card if needed :-)