The oracle agent does not support differential backup. It alsway does a "full" backup of the oracle tablespace files.
That means, if the oracle database was up and running during your backups, you would have backed it up through the oracle agent. (seperate selection under remote selections.
When restoring, you will find these backups under the restore selection marked with an own oracle agent icon.
Select the files you need and restore.
It is true, that there is NO singel button "oracle" within BE GUI. No matter whether the oracle agent is installed or not.
The agent just restores files.
In your case, after restoring the oracle agent backup, you need to recover the database from the oracle shell.
(depending on what you need, - control files, redulogs etc.)
If you did not backup the ora db with the agent but flat, while the db was running, than the backup is worth nothing ... in terms of db recovery.
If the db was offline during backup - jus perform a standard flatfile restore and have the Oracle admin do the rest.
Regards
uz