Prevent SPAM with captcha

I understand how it works, but I have a problem;
I had to implement a customized version of Securimage Captcha plugin in order to work with your extension, because of the Ajax Processing. The page that loads the Captcha image is called using Ajax therefore it wasn't display the recaptcha;

If the captcha code is valid it works, however if it is not valid it doesn't work. I'm not sure why.

The problem probably lies in the /components/com_solidres/controllers/reservation.json.php file.

In the processGuestInfo() method I have added the captcha verification and in case the Captcha code is wrong it returns this:
$response = array('status' => false, 'message' => JText::_('PLG_CAPTCHA_SECURIMAGE_VALIDATION_CODE_WRONG'), 'next_step' => 'guestinfo');
echo json_encode($response);
$this->app->close();

The Page hangs and nothing happens;

I have also changed the status to 0 instead of false for testing purposes, but it did not work either.

Can you please help?

I've attached modified files! This could really help you if you plan to implement captcha in the future!
Modification have been made to:
/administrator/components/com_solidres/config.xml (You have to configure the default captcha library OR set it up in the component options);
/components/com_solidres/layouts/asset/guestform.php (This is the Booking registration form right?);
/components/com_solidres/helpers/captcha.php (Added a captcha helper);
/components/com_solidres/controllers/reservation.json.php (Added captcha checkAnswer in the processGuestInfo() method/function)

Can you please tell me did you at least read my post previous to shared captcha files? Can you assist or no?

Modifications are done, but it doesn't work.
The post before attached files is related to my issue.

This:
And yes, I need your help with this, I don't know what else to do, thanks.