Hi there, thanks for posting and welcome back to our community.
Sorry to hear you've had issues getting your online account registered. Based on the screenshot you've provided, if you've previously been an account holder with us and you're attempting to use an email address that's previously been used with a former it account, it's highly likely that our website/system is recognising this. To help you resolve this, I would like to take closer look on your behalf. I am therefore going to send you a private message. Please keep an eye on your inbox in the top right of your screen.
Regards
Lee_R