Frame Rust problems of the 2010 Mercedes Benz C300

Tl-the contact owns a 2010 Mercedes Benz C300. While driving at various speeds the brake pedal was applied but vehicle was unstable. There were no warning lights illuminated. The vehicle was taken to mercedes-benz of louisville 2520 terra crossing blvd, louisville, ky 40245 (502) 565-4410 where diagnosed that the sub frame was rusted, broke , and un drive able but was not repaired. The manufacturer was contacted but did not assist. The failure was mileage was 94,000. Ap.