I have had the same problem:
Thank goodness that I am not alone. no one is of any help. Clearly my copy is legal and eligible for upgrade from 4.6 to 4.7.
@Mike: Unfortunately, Fb 4.5 serial keys cannot be re-used in Fb 4.7 (this is actually because of the new ability in 4.7 to have side-by-side installs of 4.5 and 4.7).
To get your complimentary upgrade serial key for 4.7, please fill out the request form at http://www.adobe.com/go/fb47_serialkey
@Neil: I apologize for the inaccurate information you've been given by support - Creative Suite 5.5 editions that included Fb 4.5 are indeed elgible for a complimentary Fb 4.7 license. Please fill out the request form at http://www.adobe.com/go/fb47_serialkey and if you have any difficulty, feel free to contact me directly via scastle at adobe.com.
Scott, thanks for helping out. It would be especially helpful to others if the customer support people knew about that information. Thanks again.