I have a IIS FTP website setup like this

\ftp\users\domain\public\public

Software that runs on clients computers logs into the FTP server by specifying domain\public and moving to public, it then uploads or downloads files / folders into that area.

I want to restrict permissions on \ftp\users\domain\public so that nothing/nobody can write files or folders here, only to \ftp\users\domain\public\public.

I setup the NTFS permissions of the folder to remove domain\users, public and server\users to not have modify right, yet I can still upload/modify files.

I have disabled inheritance from the parent folder of \ftp\users\domain\public as well.

Any ideas on what I'm missing here?

P.S I know this is a stupid setup and makes no sense, it's some bizarre legacy application that I need to migrate to a safer environment until it can be replaced.