According to iTunes a new Smart Office 2 (version 2.3.28) is available since August 22. I am currently on 2.3.27, so kept up to date. When trying to update the app, iTunes gives an error message, and I translate from Dutch:
This update is not available for this Apple ID because the update has been purchased by another user, restitution has been given for the article or the article was canceled.
None of these three conditions are valid, so maybe version 2.3.28 has been posted incorrectly on iTunes?