Change up-sells from h2 to h4

Hi

I want to change up-sells text from h2 to h4. Following is the link to a product on my site – http://www.rudragems.com/product/211gms-shaligram-nepal/
I have already changed the code from <h2><?php _e( ‘Related Products’, ‘woocommerce’ ); ?></h2> to <h4><?php _e( ‘Related Products’, ‘woocommerce’ ); ?></h4> in woocommerce/templates/single-product/related.php and also in up-sells.php but no results. Please tell me how to make this happen.

Regards
Vaibhav

http://wordpress.org/plugins/woocommerce/