.htaccess redirect not working in WordPress 3.5.1 on Apache

I’m trying to fix a canonical issue with WordPress 3.5.1

http://www.whatisanaddiction.com/index.php
needs to redirect to
http://www.whatisanaddiction.com/
so I don’t end up with a duplicate content issue with search engines.

I don’t know the code that needs to be used in .htaccess very well but I never had a problem before WordPress’ code inserted in the .htaccess.

I’ve tried all sorts of variations and many cause the whole website to “Server Error”.

Here’s what I’ve got so far but it still doesn’t redirect the index.php verions correctly.

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

RewriteCond %{THE_REQUEST} ^.*/index.php HTTP/
RewriteRule ^(.*)index.php$ /$1 [R=301,L]
    # always www
RewriteCond %{HTTP_HOST} !^www.whatisanaddiction.com$ [NC]
RewriteRule ^(.*)$ http://www.whatisanaddiction.com/$1 [L,R=301]

</IfModule>

# END WordPress

Redirect 301 http://www.whatisanaddiction.com/index.php http://www.whatisanaddiction.com/

… I see all sorts of people asking this question online but no “working” solution – so far. Maybe I’m not searching for the right terms???

Any help would be greatly appreciated!