Frankfurt-Cologne-Amsterdam-Cologne-Amsterdam

I brought my driver's license and the free international driving permit translation certificate from Zuzuche, but I didn't get the German sworn translation certificate. As a result, the German car rental company required me to take full insurance or I wouldn't be able to rent the car. I was in a hurry and didn't have time to argue, so I ended up paying over 200 euros for insurance for 6 days while the car rental itself was just over 150 euros! Last time I used rentacars.com in Germany and paid directly on the website, then went to sign the contract and got the keys without anyone asking about the sworn translation certificate or insurance.