Add billing phone and email to PIP invoice

functions.php

 function wc_ninja_add_to_billing_address( $formatted_billing_address, $type, $order ) {
	 if ( $order->billing_phone ) {
		 $formatted_billing_address .= "<br>" . $order->billing_phone;
	 }

	 if ( $order->billing_email ) {
		 $formatted_billing_address .= "<br>" . $order->billing_email;
	 }

	 return $formatted_billing_address;
 }
 add_filter( 'wc_pip_billing_address', 'wc_ninja_add_to_billing_address', 10, 3 );