aga1_

I made five phone calls to the Thrifty international phone line reservation from home in the US beforehand to make a rental car reservation and when I made my reservation I stated that my credit card would serve for insurance and I would decline the rental insurance, and none of the agents
mentioned any problem with this. In addition I arranged to get a 10% discount using my American Express card.

Arriving at the Thrifty counter in Munich airport Terminal 2, I was told that because the Munich airport location had had numerous problems with credit card companies refusing to pay insurance claims, that the Munich airport location's policy was to require written proof from the credit card company that that rental car would be covered. In addition I was told that under no circumstances could American Express be used for this, only MasterCard or Visa. As the Munich airport has no free Internet, I had to sign up for a one-hour paid service for $11.15 (€8) and downloaded both the MasterCard and Visa documents online, to show that both of my credit cards covered rental cars.
When I showed this to agent, she said I had misunderstood, and that I would require written proof SPECIFICALLY for THIS rental reservation. As an alternative, the Thrifty insurance was €250, doubling the price of my rental. When I asked for a cheaper rate, I was told I could pay €150, but I would be charged a €1200 deductible against my credit card in case of an accident.

At this point I gave up and went to one of the other rental car companies in the terminal and quickly obtained a rental car with none of the runaround about insurance.

If the Thrifty international reservation line had let me know during my 5 calls before the reservation while in the US that I would have to have written proof specifically covering this reservation, I have no doubt that I could have obtained this ahead of time.
Also, if Thrifty has a special arrangement favoring American Express cards, why did the Munich site say that even with written proof of a specific coverage that American Express cards could not be used for insurance?