01:49 PM PST: Cannot Change Plan
Some customers are unable to change their Yahoo! Small Business service (upgrade or downgrade). Please contact us through the following URL where you have the option to call or schedule a callback:
http://smallbusiness.yahoo.com/contactus
Choose your topic/issue and continue to the next page. Then you will see a phone number to call or schedule a callback.
We will troubleshoot your individual issue and take the necessary steps toward resolution. We are aware of the widespread issue and are working to resolve it in a timely manner.
04:26 PM PST
Update: This issue has been resolved.