Answer: Take a look at this law. Under Section 3068, it states in part:
(2) A person whose lien for work or services on a vehicle has been extinguished shall turn over possession of the vehicle, at the place where the work or services were performed, to the legal owner or the lessor upon demand of the legal owner or lessor, and upon tender by the legal owner or lessor, by cashier's check or in cash, of only the amount for storage, safekeeping, or parking space rental for the vehicle to which the person is entitled by subdivision (c).
If you comply with the above and they still do not turn over the car, then you will need to sue them under what is known as a declaratory judgment action and prove to the court that there is no lien on the car, that you made a demand, and offered the payment; but that tow company is refusing to comply with the law.
The best thing to do would be to hire a civil litigation attorney because of this law. The lawyer can send a demand letter threatening to collect these fees if the tow company does not want to comply.
(d) In any action brought by or on behalf of the legal owner or lessor to recover a vehicle alleged to be wrongfully withheld by the person claiming a lien pursuant to this section, the prevailing party shall be entitled to reasonable attorney's fees and costs, not to exceed one thousand seven hundred fifty dollars ($1,750).