If you want to upgrade an already purchased ticket. You simply contact our ticket vendor Tixr. They will help you with your question regarding the upgrade.
Note that we do not offer refunds of tickets unless it's for medical reasons and you can provide a medical certificate, stating you are unable to attend the event.
You are free to resell your ticket and use the "give a ticket away" -function in our ticket management system. See more info about this here.