Legal Question in Civil Litigation in California

There are several things you can do but they all must be done before the 20th. You can file an answer, you can file a motion to dispute the service, jurisdiction or how the complaint was drafted. Can't tell you more without knowing more facts.

Hope that helps and good luck and remember to file before the 20th and send a copy to the people suing you. If you need help and cannot afford a lawyer try the local bar association and see if they have a Legal Aid group in the area. Most Bar Associations do or know of one.