This seems like a very common problem! Moreover the staff on the phone lines are incompetent to deal with the issue I had a 55 minute wait to speak to them. The call was eventually cut off at the call centre end when it was clear the issue was not understood at all.
I want to transfer my existing number from Vodafone. I have the PAC code but the website isn't allowing me to set up an account to do so. It's asking for the answer to a security question but not stating what the security question is (probably because I wasn't asked to set one up).
When I try to use the forgotten password function, I receive an error message saying the system doesn't recognise my details.