Serious problems with file upload field.

Hello,
I own the premium version.
I’m using the file upload field for letting users to upload images.
When uploading an image and submitting the form, the file is attached as a link – but when downloading the image, it seems that it has been corrupted. The image doesn’t have the exact size as the original, and Windows Photo Viewer unable to open it.

Also, I’m getting a php warning error when submitting a form with file upload field, as follows:

strlen() expects parameter 1 to be string, array given - /wp-content/plugins/contact-form-by-supsystic/modules/forms/models/forms.php:181
#6 /wp-content/plugins/contact-form-by-supsystic/modules/forms/models/forms.php:19 - formsModelCfs->validateFields(Array[21], Array[19], Array[8])
#5 /wp-content/plugins/contact-form-by-supsystic/modules/forms/controller.php:353 - formsModelCfs->contact(Array[8])
#4 /wp-includes/class-wp-hook.php:286 - formsControllerCfs->contact('')
#3 /wp-includes/class-wp-hook.php:310 - WP_Hook->apply_filters('', Array[1])
#2 /wp-includes/plugin.php:453 - WP_Hook->do_action(Array[1])
#1 /wp-admin/admin-ajax.php:97 - do_action('wp_ajax_contac...')

Thank you.