I would contact Dell support: DELL support  DELL Contact Information    There should be a service tag located on your machine. Dell support is best equipped to assist with warranty related issues.  
Hi. One week ago, I bought my new R12 desktop from Fortress, HK. The retailer said it would have a three-year premium warranty. However, I cannot find a way to register my warranty information till now. Both the supportassist and dell.com show 'unable to show warranty details'. I have all the receipts (in Chinese and English) and shopping web site screeshot (in Chinese) at hand. If necessary, I can send those information for verification but I don't know how and where I should seek help.  Any suggestions for me? Many thanks for your kind help ahead.
Aurora R12, unable to show warranty details