Prestashop 1.7.5.2 How to add manually the customer vat_number on invoice

[DrizztDoUrden]

I need to add the customer delivery and billing vat_number on the invoice generated by prestashop.

I've tryed to modify my classes/pdf/HTMLTemplateInvoice.php adding 'customer_vat_number' => $invoice_address->vat_number like that:

$data = array(
            'order' => $this->order,
            'order_invoice' => $this->order_invoice,
            'order_details' => $order_details,
            'carrier' => $carrier,
            'cart_rules' => $cart_rules,
            'delivery_address' => $formatted_delivery_address,
            'invoice_address' => $formatted_invoice_address,
            'addresses' => array('invoice' => $invoice_address, 'delivery' => $delivery_address),
            'tax_excluded_display' => $tax_excluded_display,
            'display_product_images' => $display_product_images,
            'layout' => $layout,
            'tax_tab' => $this->getTaxTabContent(),
            'customer' => $customer,
            'footer' => $footer,
            'ps_price_compute_precision' => _PS_PRICE_COMPUTE_PRECISION_,
            'round_type' => $round_type,
            'legal_free_text' => $legal_free_text,
            'customer_vat_number' => $invoice_address->vat_number, // <= that doesn't works!!
        );

and also adding this to the pdf/invoice.addresses-tab.tpl

<table id="addresses-tab" cellspacing="0" cellpadding="0">
	<tr>
		<td width="50%">{if $delivery_address}<span class="bold">{l s='Delivery Address' d='Shop.Pdf' pdf='true'}</span><br/><br/>
				{$delivery_address}<br/>{$customer_vat_number} // <= that
			{/if}
		</td>
		<td width="50%"><span class="bold">{l s='Billing Address' d='Shop.Pdf' pdf='true'}</span><br/><br/>
				{$invoice_address}<br/>{$customer_vat_number} // <= that
		</td>
	</tr>
</table>

But it doesn't works!

Help please!