After being originally advised that this could not be bone through the .htacctss file, guess what?
The very same support staffer came up with the following, which works.
He has only wasted 5 days out of my schedule not to mention the time that you guys have put into helping me. Thanks again.
The following is the contents of the .htaccess file : -
redirect /index.php
http://mynewsite.com.au/catalog/index.html