Hello,
I am also experiencing this issue, I cannot register online no matter how many password variations I try.
I've tried clearing my cache, using a different browser & using a different device but experience the same problem.
I am a new customer, my broadband contract has not commenced yet, so maybe this is the issue?
It's also frustrating as I'm experiencing issues with my pre-installation and every time I call to resolve I'm recommended to create an online account, so if you could help I'd really appreciate it.
Many thanks,
Paul