if it's any help. might not be. but I've tried to access my Virgin Mobile account on and off for ages and just go round in circles - doesn't recognise m, try the forgotten password, email address and doesn't like it, tried registering and it says I'm already registered with that email address.
It turns out that because I am already a Virgin Media customer I have to use a different email address to register for Virgin Mobile - lo and behold I can now access my virgin Mobile account. Crazy as the 2 are supposedly separate yet obviously they are not if one is picking up the other.