(a) Every process left with the Commissioner shall be in triplicate. He shall return the original copy with his certificate of service which shall be accepted as proof of service of process. One copy shall be forwarded at once by mail to the company addressed to its principal office and the remaining copy he shall file in his own office. For the purpose of fixing the location of the principal office within the meaning of this section the company shall file with the Commissioner a written statement setting forth the location and post-office address of its principal office and that location and post-office address shall continue to be the location and address of the company for the purpose of this section until changed by a similar statement in writing and filed with the Commissioner.
(b) Where service is had on the Commissioner, no proceeding shall be had within 60 days after service.