reCaptcha Installed on Testimonials page in Joomla Site - But I'm still being bombarded by Spam. What can I do?

I have a website set up on Joomla 1.5.26 using RS Monials 1.5.3 to collect customer testimonials. I was getting lots of bogus testimonials that are just spam (several per day). RS Monials has a built in reCaptcha function, so I registered an account and enabled it.This was not cutting AT ALL on the spam, so I disabled the form for 3 weeks hoping the spammers would forget the site and move on. As soon as I re-enabled it, the spammers were back. I still get several per day, so they are obviously bypassing the reCapthca somehow.Can anyone suggest a better strategy to deal with these people (bots?)? -- You received this message because you are subscribed to the Google Groups "reCAPTCHA" group. To unsubscribe from this group and stop receiving emails from it, send an email to recaptcha+unsubscribe@googlegroups.com. To post to this group, send email to recaptcha@googlegroups.com. Visit this group at http://groups.google.com/group/recaptcha. For more options, visit https://groups.google.com/groups/opt_out.