如何从模板部分Wordpress主题触发表单提交

So my issue is as follows.

I'm learning wordpress and creating a custom theme. The idea was to create a dynamic modal which contains a form, that i can reuse in different places. I created the modal in the service-modal.php file and use it on the front-page.php.

My submit function is not triggering at all, so whatever I add to the submit doesn't show up, not even simple echo's.

I assume that my form action is wrong, but I can't find a similar problem/solution to look into.

Here is my service-modal.php

<?php 

    //Service modal
    //function service_modal($args){
        if(isset($_POST['submitted'])) {


            $my_post = array(
                'post_title'    => 'Test Title',
                'post_status'   => 'publish',
                'post_type' => 'inquiries'
            );


            $newpost = wp_insert_post($my_post); 


            if (!is_wp_error($newpost)) {
                echo 'success'; 

            } else {
                echo 'error';
            }
        }

        //$post = $args['service'];
        $orgTitle = get_field('title');
        $title = str_replace(' ', '', $orgTitle);
        ?>
            <div class="service-modal <?php echo strtolower($title)?> ">
                <form id="serviceInquiry" action="<?php get_permalink(); ?>" method="post">
                    <div class="service-modal-header">
                        <h4>You've selected the <span name="spackage"><?php echo get_field('title');?></span> package</h4>
                        <span class="close-modal">Close<span>
                    </div>

                    <div class="service-modal-content">
                        <div class="service-modal-content-details">
                            <h5>Selected package includes:</h5>
                            <ul class="service-list">
                            <?php 
                                for ($x = 1; $x < 7; $x++){
                                    if(get_field('item_'.$x) != ""){
                            ?>
                                    <li><p><?php echo get_field('item_'.$x);?></p></li>
                            <?php
                                    }
                                }
                            ?>
                            </ul>

                            <div class="price-group">
                                <span>$<span class="price" name="sprice"><?php echo get_field('price');?></span>/<span class="price-value"><?php echo get_field('price_value');?></span></span>
                            </div>
                        </div>
                        <div class="service-modal-content-form">
                            <h5>Leave us your details:</h5>
                            <input type="text" placeholder="Name" name="username">
                            <input type="text" placeholder="Email" name="semail">
                            <textarea placeholder="Message" name="smessage"></textarea>
                        </div>
                    </div>

                    <div class="service-modal-footer">
                        <div class="buttons">
                            <button type="button" class="cancel-btn">Cancel</button>
                            <button type="submit" class="send-btn">Send inquiry</button>
                        </div>
                    </div>  
                </form>      
            </div>
        <?php

    ?>

And I use this modal part on the front-page.php just like this:

 include( locate_template( 'service-modal.php', false, false ) ); 

As I mentioned, I somehow assume my form action is wrong, but don't rally understand why, nor can I find the solution.

If anyone knows the solution I would be really grateful if I get the "why" also, because I really would like to understand. I know that I can probably handle this form submit with ajax, but also would like to get it done this way before.