go to Customizer > Woocommerce and make an adjustment to the Thumbnail Width say 360px. And then update the Customizer. This should rebuild the thumbnails.
Hi David, the problem is the height. Not the width. Did you check the site and see the different products? Some are very tall and others not. It looks terrible.
This is because all your images are different aspect ratios. Ideally you want them all to be the same. If not possible – then try this CSS to force them: