So I've navigated the error concerning returning customers and ignored the bad advice from the site to sign up with the same email account as the contract (as per some of the support messages I've seen here).
However, my account is now stuck at the verification stage under the new email. The verification email does one of two things: direct me to a completely blank Complete Your Profile page, or redirect me to a message saying the email expired (despite being used immediately). I can confirm I'm using the correct email address for verification.
Can someone support with this please? I wish I could say it's the first problem I've experienced in the short time since I signed up for your services.
EDIT TO ADD: I've also tried requesting a new verification email, but that doesn't seem to do anything.