I'm sorry to hear you've been unable to access your mobile account over the past few days. I have checked this and it appears that that part of our site is currently under some maintenance. I have fed this back to the relevant team to find out when it is likely to be fixed and up and running again.
Our Virgin Mobile app seems to be working fine for me still, so I would recommend to use the app if you can for now, until the site has been fixed. Sorry for any inconvenience caused.
Can I ask if there was anything specifically that you were looking to do/change from your online account? We'd love to help if we can from here.