The official line is that - 'Currently, the PAYT account management system is unable to handle these requests. A workaround is expected soon'
Contract customers can request this bar presently but apparently the bar is only to be placed 'As a last resort'

It doesn't appear to be mentioned on their official web site. They don't appear to have told their customer service staff it's available. Two days ago their press office were unable to shed any light on it's existence in response to a request from the Daily Mirror.
Is the reason for their apparent reluctance to inform the public anything to do with the fact that they keep 20% of the revenue derived from this unauthorized billing?

Errrr V-SPAM isn't new at all, it's been up and running for over TWO YEARS....