The speed upgrades have generally been advised within the existing customer section of the website, and when possible either emailed out or on a letter.
For instance this year, details of the upload speed increase was in the April price change communication that was sent to every customer
http://www.virginmediapeople.com/pri...e/default.aspx
It is unworkable for every customer to be called to advise of a speed change, and Virgin only called some customers, everyone else would complain that
they didn't get a call