Add instalments in product page

woocommerceinstalments.php

<?php
add_action( 'woocommerce_single_product_summary', 'woocommerce_total_product_price', 31 );
function woocommerce_total_product_price() {
    global $woocommerce, $product;
    // let's setup our divs
    echo sprintf('<div id="product_total_price" style="margin-bottom:20px;display:none">%s %s</div>','Total do Produto','<span class="price">'.$product->get_price().'</span>');
    echo sprintf('<div id="cart_total_price" style="margin-bottom:20px;display:none">%s %s</div>','Total do Carrinho','<span class="price">'.$product->get_price().'</span>');
    ?>
        <script>
            jQuery(function($){
                var price = <?php echo $product->get_price(); ?>,
                    current_cart_total = <?php echo $woocommerce->cart->cart_contents_total; ?>,
                    currency = '<?php echo get_woocommerce_currency_symbol(); ?>';
 
                $('[name=quantity]').change(function(){
                    if (!(this.value < 1)) {
                        var product_total = parseFloat(price * this.value),
                        cart_total = parseFloat(product_total + current_cart_total);
 
                        $('#product_total_price .price').html( currency + product_total.toFixed(2));
                        $('#cart_total_price .price').html( currency + cart_total.toFixed(2));

			var coef = [1, 0.52255, 0.35347, 0.26898, 0.21830, 0.18453,0.16044, 0.14240, 0.12838,0.11717, 0.10802, 0.10040];
			$('#parcel_1 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[0]).toFixed(2)).replace('.',',')));
			$('#parcel_2 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[1]).toFixed(2)).replace('.',',')));
			$('#parcel_3 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[2]).toFixed(2)).replace('.',',')));
			$('#parcel_4 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[3]).toFixed(2)).replace('.',',')));
			$('#parcel_5 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[4]).toFixed(2)).replace('.',',')));
			$('#parcel_6 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[5]).toFixed(2)).replace('.',',')));
			$('#parcel_7 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[6]).toFixed(2)).replace('.',',')));
			$('#parcel_8 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[7]).toFixed(2)).replace('.',',')));
			$('#parcel_9 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[8]).toFixed(2)).replace('.',',')));
			$('#parcel_10 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[9]).toFixed(2)).replace('.',',')));
			$('#parcel_11 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[10]).toFixed(2)).replace('.',',')));
			$('#parcel_12 .woocommerce-Price-amount.amount').html( currency + (((product_total * coef[11]).toFixed(2)).replace('.',',')));
                    }
                    $('#product_total_price,#cart_total_price').toggle(!(this.value < 1));
 
                });
            });
        </script>
    <?php
}

@murilopratavieira esse código inclui as parcelas no sumário do produto, independente do método de pagamento. Precisa ajustar os coeficientes de correção das parcelas ali na linha 23, de acordo com as suas taxas. Se não está aparecendo provavelmente é por causa do tema ou algum outro plugin que usa o hook woocommerce_single_product_summary