I have also had this email - 3 times now over the last 3 days. However i've also had my twitter and microsoft accounts hijacked
The issue i have is access to my email - bare with me on this its strange!
I left virgin 3 years ago as i moved house and could not get virgin in the new property. My account was closed however i can still get access to my email account but only on my mobile phone! If i try and login on virgins page or change my password it doesn't even recognise my email address. I really don't know how anyone else could access it if i couldn't unless it was on my phone?
I have contacted virgin and they have said someone will be in touch, but nothing for 2 days.