Hello i have 2 dropbox accounts.1 with 5GB and Other with 2TB with different emails.on renewal annual subscription i accidently paid in 5GB account whole years payment and now my 2TB account is at stake with all data to lose.Help
I am not sure there is anything that can be done here as plans are not transferable.
All I can suggest doing is contacting support at http://www.dropbox.com/support to ask for help.
OR send a shared folder from the account that will downgrade to the one which is upgraded to move all data over to it quickly. That way you dont need to reupload everything.