Cal. Public Utilities Code § 737

All complaints for the collection of the lawful tariff charges or any part thereof, of public utilities may be filed in any court of competent jurisdiction within three years from the time the cause of action accrues, and not after, but if a public utility presents its claim or demand in writing to the person from whom the tariff charges, or any part thereof, are alleged to be due within such period of three years, that period shall be extended to include six months from the date notice in writing is given to the public utility, by such person, or refusal to pay the demand, or any part or parts thereof specified in the notice of refusal. If suit for the collection of the lawful tariff charges or any portion thereof of a public utility is filed in any court in accordance with the terms of this section, or if such collection is made by the public utility without filing suit, the person against whom such suit is filed or from whom such collection is made may, within 90 days from the date of service of summons in the suit, or the date of the collection, file with the commission, or with any court of competent jurisdiction, a complaint for damages resulting from the violation of any of the provisions of this part with respect to the transaction to which the suit of the public utility relates, or for which such collection has been made.