Credit Card Summins - California - What form do I use in response

I received a limited civil summons for a credit card debt from Brachfield & Assoc. I'd like to respond, but cannot find out what form I'm suppose to fill out. I went down to the courthouse and asked, but they told me they couldn't give me an answer, that I had to ask a lawyer. I have an idea of what I'd like to say in response, but I want to make sure I fill out the correct form so this doesn't go past the 30 days from being served and allowing them to automatically win by default. Can someone please either tell me what form to fill out, where to get it, etc. or point me in the right direction.

I’ve researched a lot of the forums (most of the day), and have not been able to find a specific reference to a form. I’m reading plenty of advise that says to respond in time (which I’m trying to do), but nothing else that is specific.