classifieds plugin contact form

the plugin is working fine except for the contact form on the classifieds page. A Captcha code is used on the form, however there is no image (ie numbers to be seen) to type in. Therefore no one can contact the publisher of the ad. Please help as i cannot use this plugin without people being able to contact the publisher of the ad. I see no place in the plugin to turn off the captcha code which would be acceptable as well.