I registered my import last October. I did it myself by faxing and e-mailing all required docs direct to VW UK.
I had no problems except I did'nt receive a VW Assist Card (which I did with previous import)
I rang VW UK a week after sending the docs and they confirmed I was registered etc.
I rang the VW Assist number two weeks later and they told me I was fully registered but that they don't send out VW Assist Cards anymore. All I needed was my reg. number etc whenever I needed them. I asked how long my import was covered and he said there was no record it was an import so I would get the same as UK supllied car
I'd bypass your delaer and ring VW UK direct, and get them to confirm you are registered. If they confirm you were registered by your dealer, then ring the VW Assist number and get them to confirm too - but don't expect a card.
What your dealer says sounds a bid dodgy to me - how would VW UK know your registration number ? and all the data about your car ? and unless they've changed their policy very recently you should definitley get 1 years VW Assist (from the date of the PDI in your sevice book)