actually, I think it is a generic link, because I could not find the kobo email anymore, so just googled it. This should work:
http://evocalize.com/consumer/busine...2dishOpinionCA
you have to enter a review for any book, and you can only do this once
per account. You will then get a code, but it is valid for
any account, so in theory of course, people could insert reviews with different accounts and use the discount on their main account...
Only thing, going by memory I think Feb 8th is the last day to upload reviews, though it would not look like this from the small print, so I may be wrong on the deadline.