Thumbnails size, rectangular

Hi, I’m having this issue, I have four boxes where I show the title of the page, the featured image and some excerpt. The issue is that the image is squared like (200×200) but I need that rectangular with the height less than the width. Why is not possible to do that? I saw the plugin gets the thumbnails dimensions from the settings > media in wordpress, but it doesn’t matter what kind of values I give there, the result is always a square picture. Can you give support with that? Best regards http://wordpress.org/extend/plugins/catalyst-excerpts-plus/