The help text for changing a username (http://uk.ebid.net/help_register.php#14) is contradictory:
In the first instance it tells the user to make the request via the Help section and then tells them to email the request (with no indication as to where to send the email).14) How can i change my username?
If you have registered and have made a mistake with your Username or have a valid reason for changing, please contact us via the Help section and if applicable we will make the necessary changes. There is a limit of 18 characters. We cannot accept spaces in the Username and characters such as stops and hyphens are not compatible, although underscores are acceptable. For security reasons please ensure you send the request from your registered email address.