How to set action in form generated by custom addon module

[carux]

HI, i've created my own addon module but i encountered an issue. When i submit the form generated, I am automatically redirected to the clientarea.php section without the function defined in the form action being executed. 

<?php
require __DIR__ . '/vendor/autoload.php';
use WHMCS\Database\Capsule as DB;
use \Ovh\Api;

add_hook('ClientAreaAction',1,function($action,$vars){
	if ($action == 'updateUsage'){
    	print_r($vars);
    	return ;
    }
})

add_hook('ClientAreaProductDetailsOutput',1, function($service) {
	try{
		$domain = $service['service']['domain'];
    	/**custom style*/
    	$style = getCustomStyle();
		$content = getAccountByDomain($domain);
    	$js = '<script src="/modules/addons/ovhmail/js/password.js"></script>';
		return $style.$content.$js;
    }catch (Exception $th){}
});

function getAccountByDomain($domain){
	/**get config variables -> applicationKey, applicationSecret, endpoint, consumerKey*/
	$config_variables = getConfigVariables();
	/**set api key*/
	$applicationKey = $config_variables['applicationKey'];
	$applicationSecret = $config_variables['applicationSecret'];
	$endpoint = $config_variables['endpoint'];
	$consumerKey = $config_variables['consumerKey'];
	/**set object Api*/
	$ovh = new Api($applicationKey,
                $applicationSecret,
                $endpoint,
                $consumerKey);	
	/**get all account linked to $domain*/
	$result = $ovh->get('/email/domain/'.$domain.'/account');
	/**order in alphabetical order*/
	asort($result);
	/**array for usage quota and updateDate*/
	$result_usage = []; $result_date = [];
	foreach ($result as $account){
    	$result_usageQuota = $ovh->get('/email/domain/'.$domain.'/account/'.$account.'/usage');
    	$result_usage[$account] = $result_usageQuota['quota'];
    	$result_date[$account] = $result_usageQuota['date'] ? date('d/m/Y H:i:s' , strtotime($result_usageQuota['date'])) : '';
    }
	return getFormManageMailbox($domain , $result , $result_usage , $result_date);
}


/**get config variables set when activated module*/
function getConfigVariables(){
	$setting = DB::table('tbladdonmodules')->select('*')->where('module', 'ovhmail')->get();
	$setting = json_decode($setting);
	$config_variables = [];
	foreach ($setting as $item) {
    	if ($item->setting != 'access' && $item->setting != 'version')
    		$config_variables[$item->setting] = $item->value;
	}
    return ($config_variables);
}

/**get custom style for element in getFormManageMailbox*/
function getCustomStyle(){
	return '	<style>
               		table tr>*{
        				padding: 5px;
        			}
        			.password-strength-bar {
            			width: 100%;
            			height: 10px;
            			background-color: #ccc;
        			}
        			.strength {
            			width: 0;
            			height: 100%;
            			transition: width 0.3s;
        			}
                </style>';
}

/**get form to set new password for account*/
function getFormManageMailbox($domain , $result , $result_usage , $result_date){
	$html = '<div id="container-form-manage-mailbox">
    			<div class="header-lined">
                	<h1>Gestione caselle per il dominio '.$domain.'
                </div>
                <div class="update-usage-mailbox-form">
                	<form method="post" action="clientarea.php?action=updateUsage">
                    	<h3>Aggiorna lo spazio utilizzato dalle caselle nel tuo dominio</h3>
                        <button type="submit">Aggiorna</button>
                    </form>
                </div>
                <div class="set-new-password-mailbox">
                	<table>
  						<thead align="left" style="display: table-header-group">
  							<tr>
     							<th>Casella email </th>
     							<th>Spazio utilizzato</th>
     							<th>Ultimo aggiornamento</th>
     							<th>Scegli Password </th>
     							<th>Ripeti Password</th>
     							<th></th>
   
  							</tr>
  						</thead>
						<tbody>';
	/**print mailbox row by row*/
	$i = 1;
	foreach ($result as $email){
    	$html .= '			<tr>
        						<form method="post" action="">
    								<td><input type="hidden" name="account" value="'.$email.'">'.$email.'@'.$domain.'</td>                                    
            						<td>'.$result_quota[$email].'</td>
            						<td>'.$result_date[$email].'</td>
        							<td>
            							<input type="password" name="new_password" id="password-'.$i.'"/>
    									<div class="password-strength-bar" id="password-strength-bar-'.$i.'">
        									<div class="strength" id="strength-'.$i.'"></div>
    									</div>
									</td>
            						<td>
            							<input type="password" name="repeat"/>
            							<div style="display:none" id="password-match-message-'.$i.'">Le password non coincidono.</div>    
            						</td>
            						<td><button type="submit" id="change-password-'.$i.'" style="display:none">Cambia password</button></td>
        						</form>
                            </tr>';
		$i++;
    }
	/**path to js function*/
    $html .= '			</tbody>
    				</table>
    			</div>
                <div class="make-new-mailbox">
                	<h2>Crea una nuova casella per il dominio '.$domain.'</h2>
					<table>
                    	<thead>
                        	<tr>
                            	<th>Nome account (non inserire @dominio)</th>
                				<th>Descrizione</th>
                				<th>Password</th>
                				<th>Spazio da utilizzare</th>
                				<th></th>
                            </tr>
                        </thead>
        				<tbody>
        					<tr>
            					<form method="post" action="">
            						<td><input type="text" class="new_mailbox" name="new_account"></td>
                					<td><textarea class="new_mailbox" name="description_new_mailbox"></textarea></td>
        							<td>
            							<input type="password" class="new_mailbox" name="new_password" id="password-'.$i.'"/>
    									<div class="password-strength-bar" id="password-strength-bar-'.$i.'">
        									<div class="strength" id="strength-'.$i.'"></div>
    									</div>
									</td>
                					<td><input type="number" class="new_mailbox" name="usage_quota_new_mailbox" value="5000000000"></td>
                					<td><button type="submit" id="new_mailbox_btn" style="display:none">Crea casella</button></td>
            					</form>
            				</tr>
        				</tbody>
                    </table>
                </div>
                ';
	$html .= '</div>';
	return $html;
}


?>

Thank you soo much for helping.