class-tb-compat-woocommerce.php

<?php
/**
 * Up sell product display. Override Woo's woocommerce_upsell_display().
 *
 * @since 2.5.0
 */
public function up_sell() {

	$args = apply_filters('themeblvd_woocommerce_up_sell_args', array(
		'posts_per_page'	=> '-1',
		'orderby'			=> apply_filters('woocommerce_upsells_orderby', 'rand'), // woo default filter, let's keep it for compat
		'order'				=> 'desc',
		'columns'			=> $this->loop_columns()
	));

	woocommerce_upsell_display(
		$args['posts_per_page'],
		$args['columns'],
		$args['orderby'],
		$args['order']
	);

}