Hi,
First many thanks to Nick for all the great work done with rclone. 
I have noticed that since the end of April 2017, the mainpage of ACD : https://www.amazon.com/clouddrive/ has changed and now the “Unlimited Storage” appears in small letters (see for instance the previous look : https://web.archive.org/web/20170401232408/https://www.amazon.com/clouddrive/home?ref_=cd_auth_home).
Fingers crossed