Huk24 second car

Hello, my wife has insured our Audi A4 at the Huk24 – all-inclusive with 45%. Now we have bought another used MX-5. Again my wife has insured this through the HUK24 – as a second car with partial cascade. Shortly after the beginning of insurance came the police – we were also classified here with partial cascade 45%. It all looked wonderful. Today, 3 weeks after conclusion of contract, a bill from the Huk24 flutters into my house. Our first car – the A4 – is now available as a second car. It is rated 50% worse than our MX-5 (our actual second car). I am supposed to pay back for the Audi since MX-5 registration date and pay ~120€ more in the future per quarter. Thus, the Audi A4 will be twice as expensive (~500€/year more than before)!!! I have questions about this: 1. I was not informed about this second car regulation with 50% worse classification anywhere and the insurance certificate for the MX-5 did not recognize this. Is this valid? 2. Why is the r Audi classified as second car/regraded (i.e. the car which is significantly more expensive in the insurance), whereby it is clearly the first car (should also be recognized by the indicated kilometers/year). 3. Do I get out of it before the end of the year? If I had known that I would have registered the car on me. I feel cheated and ripped off 🙁 I would be really grateful for tips Sven