25% discount applies to all Beats, SkullCandy, Moki, Phillips, Panasonic and Sony headphones at full prices only, not on discounted/special pricing. Offer valid for 2 weeks once you create an account.
You can make a My Coke account at https://www.coke.co.nz/mycoke/
Once an account is made you should get a message in your site inbox with a 'unique code' and details how to order an item(not via the webstore but via email).