Zynga's customer service line is answered by an automated system. It gives you three options: customer support information, investor relations, or human resources. If you choose customer support information, you just get a recording about the support resources they offer. They give you the website for their online support and provide a different phone number to call for billing support. It then takes you back to the main menu.
The other two options won't get you to a human, either. Selecting investor relations once again lists the help page URL and billing support number, then transfers you to a mailbox to leave a message. For the human resources option, it says the person at this extension is unavailable and sends you to a mailbox. I didn't try leaving a message since they weren't related to my questions, but I'm not sure if that will get you a callback or not. There's no other way to talk to anyone with this phone number.
Most of Zynga's support is on their website. They have separate pages for each of their games. Once you select a game, it takes you to a collection of articles that cover troubleshooting, account issues, billing questions, tips, and guides for the game. There is a "Contact Us" option at the bottom of the page. It takes you to a form asking for your contact information and a description of your issue. It looks like each game has its own unique form. You have to select one of the games to get any further into the support resources; there's no general support page.
The billing support number they provide is 800-762-2530. You can reach a human agent with this number, but only for billing help. The line is answered by a menu asking you to choose technical support or billing support. If you opt for the first one, you get a recording listing the support website URL again. It goes on to say that most issues can be addressed online, and if you need further help you can contact them there. It said that Zynga and its related companies do not offer phone support for gameplay or technical issues, and billing specialists aren't trained to assist with anything besides billing.
If you choose billing support, they provide the webpage information and then transfer you to an agent. I was only on hold for a few seconds before someone answered and asked for my email address. Unfortunately, my issue wasn't related to billing, so I couldn't get help over the phone. I had to look for an answer on the webpage. They have a lot of information available, but not much beyond basic troubleshooting if something's wrong.
If you need billing help from Zynga, you can speak to a human with the second number. 855-449-9642 won't get you to anyone. The mailboxes are only for investor questions or HR help, presumably for their employees. For technical or gameplay help, the only option you have is their website.