Panda 30,000 km brake discs defective – no culling

Hello, last week I noticed that my Panda (bj 2010, 30.000 km driven) makes a loud noise when braking. I drove to the next workshop (a pitstop) and had a look what it is. The mechanic said that the brake pads and the brake discs at the front left are completely finished. He also did not let me drive and repaired the car the same afternoon. He put the broken parts in my car as proof. The brake caliper had after I asked if you didn’t have to see it during the inspection. He said no, that happened at short notice. He specifically said that this was not normal wear, since the brake discs are only due from approx. 100,000 km. (He cleaned the caliper, then it was possible again). The whole cost 210 euros (and that was probably no longer necessary). I called my Fiat dealer today and asked if there was anything to be done with the guarantee. Whether I could get the money back. He said no. On the grounds that… 1. Brakes only up to 15,000 km warranty would have been made at Fiat and 2. I did not have the inspection done at a FIAT dealer. During the inspection this should have been noticeable. I am pissed off! What can I do? I thank you in advance for advice.