Legal Question in Civil Litigation in California

It sounds like you have a good case for a motion to quash, but really what good does that do you? They will just find you and serve you again, properly this time. Motions to quash are rally useless unless they are in support of a motion to set aside a default or judgment. Otherwise, you have notice of the action, you have the complaint. You know enough about the system to figure out that they have filed a proof of service. Save your time and money and just file an answer and get on with defending or settling the lawsuit.

If your neighbor is willing to testify that the process server asked for your physical description then yes, you may have a very good motion to quash and you may have a good lawsuit against the process server for filing a false return of service. Eventually though you will have to defend the lawsuit. Consult an attorney.

I agree that you have grounds for a motion to quash, as that is not proper service. Unfortunately, all a motion to quash will do is delay everything, and you will get reserved. (Or maybe not at all this time, given the quality of the service by your opponent.)

You may want to speak to an attorney and look into defenses to the case.