I can't search because a Captcha keeps failing. There's no one to tell. Who has responsibility for this? Where can I click to report the problem?
If you really have a problem, you should report it on either your site meta (for a site-specific problem) or this site, meta.stackexchange.com (for a network-wide problem). In either case, ask it as a question, use the bug tag to indicate that you think it is a bug, and add relevant tags to further indicate the scope of the question.
See Where is the best place to ask questions and report bugs about SE sites? for more details.