Change text on ProSite checkout page

Howdy,
Currently on the checkout page for prosite, if the account is free is say's
"Upgrade "Site Name" (domainname.com) - Not Pro Site"
Is there a way for it to say the name of the level, e.g. Freemium, instead of what it isn't.
As using the Rebrand Pro Site label doesn't make much sense.
Cheers,
D