Clear installments on payment method change

Question

My store have two payment methods, one based on credit card and another bank transfer. If I choose credit card and choose to installments, Magento update subtotal adding taxes.

If I give up to pay with credit card and change to bank transfer (who should't have taxes), the taxes of installments persists. How can I clear installments in this cenary?

I tried to use those events:

• checkout_type_onepage_save_order_after
• sales_order_place_after

But it is not triggered when I change the form of payment. Only when saved.

Answer 1

I solved creating event sales_model_service_quote_submit_before on ModuleVendor/ModuleName/etc/events.xml:

<?xml version="1.0"?>

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_model_service_quote_submit_before">
        <observer name="mpfix" instance="ModuleVendor\ModuleName\Observer\Mpfix" />
    </event>
</config>

And the observer:

<?php

namespace ModuleVendor\ModuleName\Observer;

use Magento\Framework\Event\Observer as EventObserver;
use Magento\Framework\Event\ObserverInterface;

class Mpfix implements ObserverInterface {

    public function execute(EventObserver $observer) {
        $order = $observer->getOrder();
        $quote = $observer->getQuote();

        if($order->getPayment()->getMethod() == "payment_method_code"){ //code of payment method 
            $quote->setFinanceCostAmount(0);
            $quote->setBaseFinanceCostAmount(0);
            $quote->save();

            $order->setFinanceCostAmount(0);
            $order->setBaseFinanceCostAmount(0);
            $order->save();
        }
    }

}