Thanks for your reply but call forwarding is active.
In voice call settings "always forward" is disabled, but "forward when busy", "forward when unanswered" and "forward when unreachable" all show forward calls to +447458333222. when trying to disable these settings the message "Failed to read data Unexpected response from network". No number is set in the voicemail section.
Also when I do not answer incoming call it goes to voicemail.
I have had customers call my mobile and say they have left a message when they could not reach me on my mobile.
I could therefore be losing business because of Virgin's bad service.