Brake Hoses, Lines/piping, And Fittings problems of the 2001 Chevrolet Tracker

The entire undercarriage has rotted, including the brake lines, oil lines and antifreeze coolant lines. I do not believe this is normal for any car, even though the car is 12 years old. It was happening to the previous owner but he was reluctant to report it. . . I am not. I have owned the car only for about 4 months now. I have had to replace some of the coolant lines and some of the brake lines. Now the oil lines are leaking heavily and I am going to have to have them replaced as well. Also, the previous owner said that when a passenger tried to use the seat belt it completely locked up on the front passenger side. I have not been able to have a passenger int he front seat because it is illegal to have a passenger ride without a seat belt. I feel that the car should b e repaired by general motors since I feel the steel used in building this car was not properly coated, thereby causing this severe deterioration of the undercarriage. I had to be towed when the brakes failed going down rt. 739 in pennsylvania, just before a huge hill/downgrade in the roadway. Now the coolant lines are leaking due to rust and so are the oil lines.