My question involves collection proceedings in the State of: CA

A law firm representing a credit card that is no longer on my credit report(statute of limitations has run out) has contacted me.

I received these forms from the law firm: Notice to Consumer or Employee and Objection, Deposition Subpoena for Production of Business Records, and Subpoena Duces Tecum. These were apparently sent out to the credit card companies I currently deal with now. This law firm is seeking records from them for examination such as copies of credit application, checks used for payments, etc. What should I do with this? Is this even worth taking legal action on since the SOL has passed?