Customise width and height of WooCommerce images since the way it handles images changed in 3.3. More detail on these filters at https://github.com/woocommerce/woocommerce/wiki/Customizing-image-sizes-in-3.3

woo-custom-image-sizes.php

<?php
// Customise the product image and gallery thumbnail to ensure they match
function doublee_custom_woo_images() {
	return array(
		'width'  => 600,
		'height' => 476,
		'crop'   => 1,
	);
}
add_filter( 'woocommerce_get_image_size_gallery_thumbnail', 'doublee_custom_woo_images' );
add_filter( 'woocommerce_get_image_size_thumbnail', 'doublee_custom_woo_images' );
add_filter( 'woocommerce_get_image_size_single', 'doublee_custom_woo_images' );