Yes, you are correct as far as admin/users_update.php is concerned; but I have a file in the same directory as follows admin/user_update.php which has the rogue linked files.
I am now beginning to understand, would it be possible that admin/user_update.php is not being used and that this is a rogue file??
Just to add to the confusion, I am not having a problem with the execution of PowerStore, I am just exploring.