this won't work in this case. The site is being specifically targetted. A custom captcha will be trivial to bypass. The reason it worked for you would be your s

this won't work in this case. The site is being specifically targetted. A custom captcha will be trivial to bypass. The reason it worked for you would be your site was just bulk scraped and no patterns could be found in your captcha to match it to a solving solution so the spammer moved on to the next. When your site is specifically targetted, captchas will not work