Do you mean changing the email address used when logging into your Virgin Media cable account? If so, have you tried logging into your cable account to change it to the email address you want as you should be able to do this.
Its the original email for the account everything relating to it is linked billing, information updates or contract changes go to that email and cant seem to change it. Looking online on here eems you can only change it via technical and under special circumstances
Thanks for your post and welcome to the community forums. If you are able to access to your self-care account, here you can change the email address used to log in, under My Details>Login. However the primary email address will always be marked as primary on the media account cannot be changed.