Gear damage

Good morning! My Juke Automatik, 7 years old and only 35,000 km has a gearbox damage. Of course, it is completely incomprehensible to me. Rep. costs approx. 6.500, car to the dealer sell approx. 3.000. I am really pissed off, because of course I have not even 6.500 € in the “Portokasse”. That one can make a certificate request to Nissan, I had to tell the dealer – he did not do it on his own. Therefore no info this is reasonable yet. For tips, infos, experiences all I’m kind of grateful because I like my car and I want to keep it.