.htaccess Redirect Doesn't Work / Hosting Redirects Automatically to a Defined Page

I'm making a SEO work for a website that designed by someone else and I had to change url's of some pages. But they have old url's in google searchs still. So I want to redirect them to new pages in my .htaccess.

But no matter what I do, I get the error:

"The resource you are looking for has been removed, had its name changed, or is temporarily unavailable."

I tried

RedirectMatch 301 ^/contact\.php$ /contact-us.php
RedirectPermanent /contact.php /contact-us.php
ErrorDocument 404 /error.html

I also tried to create the old page just to see if it doesn't redirect because of it's unexistence.

The hosting company has a CPanel(Parallels Plesk Panel 9), I guess it's what causes this, but "Custom Error Documents" section is tu开发者_运维技巧rned off. I turned it on, there's an "error_docs" folder, it redirects to "not_found.html". And I can't change those pages or delete because "I don't have permissions".

This is the URL. My current .htaccess file is:

RewriteRule ^([^\.]+)$ $1.html [NC,L] 
RedirectPermanent /default.htm /index.htm

Try this:

Options +FollowSymLinks -MultiViews
DirectoryIndex index.htm
ErrorDocument 404 /error.html

RewriteEngine On
RewriteBase /

RewriteRule ^contact\.php$ /contact-us.php [NC,L]
RewriteRule ^default\.htm$ /index.htm [NC,L]

RewriteRule ^([^\.]+)$ $1.html [L]

If still nothing -- then contact your hosting company -- they should know for sure.