You need a PAC
If you want to bring your number with you, you’ll need a Porting Authorisation Code, usually called a PAC.
When you use a PAC your old airtime plan will be cancelled as soon as the switch completes. That means you won’t need to serve a notice period with your old provider or pay double the bills.
Call your old network ask them it should arrive in a few hours. Call Virgin give them the details (PAC code), they process it should be done in... Two working days