Opencart contact form sends data via get method instead of post

Question

I am using Opencart version 2.1.0.1. There is nothing changed in the contact form much. The contact form is sending the data in the GET method but it is supposed to send the data in POST method as the validations are being done for POST data. Can someone please tell me what could be the issue. https://www.ijminc.com/index.php?route=information/contact is the website link for the contact page I am talking about.

if (($this->request->server['REQUEST_METHOD'] == 'POST') && $this->validate()) {
        // echo $this->request->post['is_redirect'];
        if(empty($this->request->post['is_redirect'])){
            $mail = new Mail();
            $mail->protocol = $this->config->get('config_mail_protocol');
            $mail->parameter = $this->config->get('config_mail_parameter');
            $mail->smtp_hostname = $this->config->get('config_mail_smtp_hostname');
            $mail->smtp_username = $this->config->get('config_mail_smtp_username');
            $mail->smtp_password = html_entity_decode($this->config->get('config_mail_smtp_password'), ENT_QUOTES, 'UTF-8');
            $mail->smtp_port = $this->config->get('config_mail_smtp_port');
            $mail->smtp_timeout = $this->config->get('config_mail_smtp_timeout');

            $mail->setTo($this->config->get('config_email'));
            $mail->setFrom($this->request->post['email']);
            $mail->setSender(html_entity_decode($this->request->post['name'], ENT_QUOTES, 'UTF-8'));
            $mail->setSubject(html_entity_decode(sprintf($this->language->get('email_subject'), $this->request->post['name']), ENT_QUOTES, 'UTF-8'));
            $mail->setText($this->request->post['enquiry']);
            $mail->send();
            
            $this->response->redirect($this->url->link('information/contact/success'));
        }

In contact.tpl, the form code is as

<form action="<?php echo $action; ?>" method="post" enctype="multipart/form-data" class="form-horizontal">
    <fieldset>
      <legend><?php echo $text_contact; ?></legend>
      <div class="form-group required">
        <label class="col-sm-2 control-label" for="input-name"><?php echo $entry_name; ?></label>
        <div class="col-sm-10">
          <input type="text" name="name" value="<?php echo $name; ?>" id="input-name" class="form-control" />
          <?php if ($error_name) { ?>
          <div class="text-danger"><?php echo $error_name; ?></div>
          <?php } ?> 
        </div>
      </div>
      <div class="form-group required">
        <label class="col-sm-2 control-label" for="input-email"><?php echo $entry_email; ?></label>
        <div class="col-sm-10">
          <input type="text" name="email" value="<?php echo $email; ?>" id="input-email" class="form-control" />
          <?php if ($error_email) { ?>
          <div class="text-danger"><?php echo $error_email; ?></div>
          <?php } ?>
        </div>
      </div>
      <div class="form-group required">
        <label class="col-sm-2 control-label" for="input-enquiry"><?php echo $entry_enquiry; ?></label>
        <div class="col-sm-10">
          <textarea name="enquiry" rows="10" id="input-enquiry" class="form-control"><?php echo $enquiry; ?></textarea>
          <?php if ($error_enquiry) { ?>
          <div class="text-danger"><?php echo $error_enquiry; ?></div>
          <?php } ?>
        </div>
      </div>
      <?php echo $captcha; ?>
    </fieldset>
    <div class="buttons">
      <div class="pull-right">
        <input class="btn btn-primary" type="submit" value="<?php echo $button_submit; ?>" />
      </div>
    </div>
  </form>

Note : I have been working on this issue for 2 days now and did a lot of google search. I couldn't get any relevant answer that could solve my problem. If you guys have any link that could solve my issue, please post it.

Thanks for the help in advance.