We've learnt from a few people that in the last days the promocode KIZOMB for booking accomodation at Novotel Hotel wasn't working properly online. We are trying to find the reason for that and fix it ASAP.
In the meantime you can try calling the hotel directly, the price for the festival nights should be 195 PLN a double and 175 a single room INCLUDING breakfasts. Don't accept anything higher than that! :)