[Plugin: Contact Form 7] Still getting spam even with CAPTCHA

Hello.

I’m using the Contact Form 7 plugin around my entire website. All of the forms have CAPTCHA images included, but one form still seems to get a lot of spam.

Is there any way to decrease the amount of spam on this specific form (bots are constantly sending emails)? Again, I’m using CAPTCHA on it, but that doesn’t seem to help (or, not help anymore).

Thanks!