use of featured image and media with downloads

When creating downloads I have to have a copy of the image I want to appear with the download on the page both in the box on the downloads screen (obtained by clicking on media button) and in the featured image box. Without both it does not appear. However, when I click on the pic on the web page to see the product in greater detail it goes (as it should) to a page that only shows that product, but it now shows two pics – the correct one and the partial one that appeared in the featured image box. What am I doing wrong? I only want to see the single complete image.
http://www.westcountrybookworm.co.uk/off-the-shelf-book-recommendations/book-recommendations-for-12/
This is a webpage that will demonstrate what I mean. Click on one of the products with a pic to follow through.

Quite separately I would like to get the price to display beneath the text on this product page, but frankly that is a much less important problem.
Thanks for your help.
Marion

http://wordpress.org/plugins/easy-digital-downloads/