CakePHP sending HABTM checkboxes values through email

I am developing a Poll Form to be filled by our customers. In that form there are radio options, textboxes, and a group of checkboxes. I am only having trouble getting the values of the checkboxes being send through email. The checkboxes are displayed by using a HABTM relationship between the tables Polls and Listexcursions. I am using ViewVars like the following manner(PollsController.ctp):

public function add() {
    App::uses('String', 'Utility');

    if ($this->request->is(array('post', 'put'))) {
        $this->Poll->create();
        if ($this->Poll->saveAll($this->request->data)) {
            $email = new CakeEmail(); // Create a new instance
            $email->template('poll', 'default') //Use poll for the view (app/View/Emails/html/poll.ctp), and default for the layout (app/View/Layouts/Emails/html/default.ctp)
                ->emailFormat('html')
                ->from('no-reply@hovertours.com')
                ->to('google@hovertours.com')
                ->subject('Valoracion de Servicios - Encuesta')
                ->replyTo($this->request->data['Poll']['email'])
                ->viewVars(array(
                    'name' => $this->request->data['Poll']['name'],
                    'email' => $this->request->data['Poll']['email'],
                    'question01' => $this->request->data['Poll']['question01'],
                    'question02' => $this->request->data['Poll']['question02'],
                    'comments' => $this->request->data['Poll']['comments'],['comments04'],
                    'listexcursion' => $this->request->data['Listexcursion'],
                ))
                ->send();
            return $this->redirect(array('action' => 'poll_received'));
        } else {
            $this->Session->setFlash(__('The poll could not be saved. Please, try again.'));
        }
    }

    $listexcursions = $this->Poll->Listexcursion->find('list');
    $this->set(compact('listexcursions'));
    $this->layout = 'design';
}

My poll email layout (app/View/Emails/html/poll.ctp) is the following:

<table cellpadding=10 cellspacing="0" width="30%" border="1" style="border-color: #666;">
<tr>
    <th width="40%">Excursiones</th>
    <td>
        <?php if (!empty($poll['Listexcursion'])): ?>
            <?php foreach ($poll['Listexcursion'] as $listexcursion): ?>
                <?php $listexcursions[] = $listexcursion['name'] ;?>
            <?php endforeach; ?>
            <?php echo String::toList($listexcursions, 'y '); ?>
        <?php endif; ?>
        <?php
            echo "-----";
            echo #String::toList($listexcursion);
            print_r($listexcursion);
        ?>
    </td></table>

My Model Poll.ctp is:

class Poll extends AppModel {
public $displayField = 'name';
public $hasAndBelongsToMany = array(
    'Listexcursion' => array(
        'className' => 'Listexcursion',
        'joinTable' => 'polls_listexcursions',
        'foreignKey' => 'poll_id',
        'associationForeignKey' => 'listexcursion_id',
        'unique' => 'keepExisting',
        'conditions' => '',
        'fields' => '',
        'order' => '',
        'limit' => '',
        'offset' => '',
        'finderQuery' => '',
    )
);

function beforeValidate($options = array()) {
    if(!empty($this->request->data['Listexcursion'])) {
        $this->data['Listexcursion'] = implode(',', $this->data['Listexcursion']);
    }
    return true;
}

I've tried using implode function in my email layout and in the model by using the beforeValidate function, but I get a blank results. I've used a foreach function as well. Most of the time I get a notice (8) array to string conversion error. I've been trying all kinds of solutions found here in SO but I can't get to the solution I need.

Any help would be appreciated.