If you have already bought a ticket, but would like to upgrade it (perhaps from a 3-day ticket to a 4-day ticket, or from a self-funded ticket to an employer-funded ticket), you can purchase an upgrade.
Within the limits of our ticketing system, the simplest way for us to allow you to do this has been to create a special ticket with a "pay what you want" price field. Of course, you shouldn't actually pay us what you want! You should calculate the difference between the price of your original ticket and the price of your new ticket.
Once you've purchased your upgrade, you'll be asked for your original ticket reference number. We'll then be able to upgrade your ticket for you.
Get in touch if you have any questions!