How should I do that I can not find out where send the cour

Thanks for answer .But completely different company.

First of all.This case is personal case suing not company.
Second .All the Corporation Name Agent for Service of Process--
CITIBANK (BANAMEX USA) ALFREDO SANCHEZ
CITIBANK GLOBAL INVESTMENT TECHNOLOGY, INC. C T CORPORATION SYSTEM
dissolved CITIBANK SERVICE CORPORATION C T CORPORATION SYSTEM , were not the company that I am suing .I had have tried .i.e.CITIBANK (BANAMEX USA) ALFREDO SANCHEZ
They said : their name is CITIBANK (BANAMEX USA)ALFREDO SANCHEZ --actually the name just changed from others about few moonths ago, does not have any relative with CITIbnak(South Dakata) .completely different company.