Their service isn't the greatest, I bought a new b...

Their service isn't the greatest, I bought a new bmw and the electrical corroded and now the rear view camera doesn't work. If that's not all the parking sensors don't work either and they refused to repair it because it's is corrosion not because of manufacturer error. Well if they did it right shouldn't that not happen? It said water got into the system so that's why the wires corroded and they refuse to fix it because it is due to the owners failed action to take care of the vehicle I don't understand why it is the owner's responsibility to make sure the wires don't corrode