How do I upgrade my subscription mid cycle?

Visit, press 'My Account' and login with your User ID (often an email address). Choose the new subscription you'd like to upgrade to and click the "Upgrade Now" button. The subscription's full price will be displayed, however the next screen takes into account your remaining length in the billing cycle and the type of subscription, to work out the exact value required for any upgrade. You will not double-up on subscription billing when processing an upgrade.