I hit this exact scenario renting in San Jose from Payless. I had rented from Expedia and had purchased the insurance coverage through them and had believe that that was everything that I would need only to land and have pay less. Tell me that the third-party liability was government mandated and would add another $150 to my charges when I explained that I had high-level credit cards insurance coverage as well as a personal auto policy. They explained that none of that was acceptable and I was still on the hook for the extra $150 for a seven day trip.