Hello Estelle -
You have a background image set in your template for the unordered list. The first thing you need to do is go into your template.css and remove that background image. If you need it for the rest of your site, then you need to create a CSS for a suffix that can be used. The plain, vanilla UL, however, should have no background.
After you get rid of that image, then your images will be able to render closer together. At first glance, it looks like you don't have enough space to render two full images in that module space. You said that setting the images to vertical didn't work either, so first thing you do is to get rid of the background image. Then look at your result. If you leave the scroller horizontal and set it to show just one product at a time, then the image is probably just fine, correct? If one is fine, but the second is cut-off then you simply have a space problem.
Let us know how things look once the background image is gone.
Thanks for buying our scroller!!!