You could try the Next Generation Text Relay app, as that's available on computers and smartphones:
https://www.ngts.org.uk/
This works for all departments as it uses an hearing operator to call Virgin Media.
Alternatively you could try the Virgin Media Text service that's mentioned on this page using any mobile phone:
https://www.virginmedia.com/accessibility/virgin-phone
However I'm not sure if that currently covers the cancellation teams or whether it's a Customer Services team only.