Audi 1.9 % financing, KSB requirement

Hello, we bought an Audi A4 factory service car yesterday via an Audi center or financed 1.9%. In case of signing, the seller came around the corner with a KSB Plus (approx. 1000 euros). On request, he said that the KSB must be taken otherwise it cannot be offered to us on the terms and conditions. Since we absolutely wanted the car, we agreed for the time being. Yesterday evening I again agreed to the terms and conditions (europ. standard info consumer info) durc hlest. Here it is clear that the insurance is not a prerequisite for the credit (is insurance mandatory prerequisite for the credit -> No). Furthermore, in case of collateral for the credit only the salary and the car stands. Therefore I could withdraw the KSB plus nevertheless without endangering the credit agreement or? Does one already have experience with it and can help me? I want to call in the car dealership today and ask again, unfortunately the Verk Don’t spend the week in the house and I’d like to do it.