Recursively chmod certain file types using a custom command

Have looked everywhere for some info on this but can't find it. Here's a summary of what I'm trying to do.

I don't have shell access to my server and need to remove group execute permissions recursively on all html files in all directories (I have thousands of directories). I can create a custom command that changes the permissions on selected files or directories using...

SITE CHMOD 765 %fa

But as soon as I add the -R switch to make this happen recursively, e.g...

SITE CHMOD -R 765 %fa

It generates an error.

I have tried using the g-x switch (SITE CHMOD g-x %fa) to only update the group execute bit (the ideal solution) but that simply wipes all the permission settings for the file.

What I'm trying to achieve is equivalent to the following shell command:

chmod -R g-x *.html

or if that isn't possible then...
chmod -R 765 *.html

SmartFTP has a recursive option but I don't want this change to impact on all files, only *.html files.

Is the above possible?

Thanks in advance y'all.

This is a server side issue. The SITE CHMOD command does not accept the same arguments as the usual "chmod" command on the shell. This is probably because the FTP server software you are using is not able to pass additional arguments it receives via the SITE CHMOD command to the underlaying "chmod" shell command.