I got this email which is meant to be for old customers, but I just changed the email in the URL and created a new account under that email and it worked.
(Replace youremail%40domainname.com with your email address, and use %40 instead of the @ symbol.)
Or you might be able to sign up a new account and enter promo code 'Reactivate_Sept2013' - I haven't tested this method.
Free for 2 months of unlimited streaming and/or DVD's.
Cancel anytime before it renews (go here: https://secure.quickflix.com.au/member/myaccount or you can delete the PayPal Agreement).