Been through it today, took 3 hours of online chat and telephone calls to sort it for 2 numbers I have in my name!
If you haven't got a 2nd email address (that you have never used with Three), create one! Gmail or Hotmail etc.
Try and register with that new email address. If it doesn't register, then Three support have to reset it their end. If it does work, then you will still need to speak to Three support and ask them to change it too the email address you really want, whether old or new, and only then will it work.
Even though both my numbers are sorted and work on the app, the website is still saying it doesn't recognise my number!
Three have completely broken their system with this update and you have to go round the houses to get it fixed. Good luck!
