I have a Virgin Mobile account which was originally registered with an email address which is now defunct. As a result, payment reminders have not come to me, and I've today received a postal letter which asks me to pay up or risk court action!. No Virgin contact number that I can find actually leads to a human being at the moment - all you get is a texted link pointing back to the (to me) useless web help pages.
I cannot log in to change my profile, because I am not sure of my login name - if it's the redundant email address that's expected, it won't be any use, anyway, because any reply will go into the same black hole.
If you click on the "I've forgotten login and password" option, you have to give account number, surname and area code - which can only be found on copies of the bill which, again, I do not have, since the bills were all emailed to the dead email address! I tried all the area codes in the drop-down in turn anyway, and none of them logged me in to anything.
Although I admit it was my fault not to have changed the email address when I could, I still think Virgin have not thought of the impossible situation I am now in... There is a potential further complication in that I do not actually use the phone myself - I donate its use to a not-for-profit organisation, which actually keeps it.