You will get the sim within a few days and ringing 789 will ell you what is left on your bill completely for free the 10p charge is only for calls to speak to an agent and is called a connection charge.
You should also be able to check out your monthly statement online as well.
The is a customer offer for £10.99 which includes a Blackberry 9300 with 100 minutes, 500 texts, 500mb wifi and 3000 texts to other Virgin Mobile phones
https://www.virginmobile.com/vm/view...ingId=11257264