Chmod change

It might still be possible through a desktop FTP client. The PHP chmod function is disabled and the file manager just doesn’t have this feature, but the FTP server itself may still work.

This is an unfortunately case though. I can tell you with absolute certainty that whether the directory has permission 755 or 775 has absolutely zero consequences to the functionality of your website, and the only reason your website “requires” it is because the developer of the software doesn’t have a good understanding of file permissions.