If you click the following website, it is already filled in and the 15% is applied to the best available rate. Kamers (radissonhotels.com) You have to book with the promotional code: DCR20. (Only valid when presenting your entrance tickets 'The luminous nights' at check-in)
(Enkel geldig bij het voorleggen van je entreetickets 'De lumineuze nachten' bij het inchecken)