Its weird how it works for you but not for others. I've ordered an A6 a couple of weeks ago, due in December, but it isn't the car that is making the difference, it just refuses to allow me to log in. I've tried creating a new account, tried different browsers, and tried on my phone, all just show up that same "service unavailable" message.
How is your car getting delivered so quick? I ordered my S3 back in early August and have an expected delivery of around March.