For the past few months, I have heard a loud rattling noise coming from under my car. It makes this noise whenever I drive around town. It also makes this noise when I rev it while in park between 1,500-3,000 rpms. I did a google search and determined the ceramic piece inside of my catalytic converter was broken. I made an appointment at the Ford dealer and dropped my car off. The next day, I got a phone call from the service manager and he said the technician could not get my car to make the rattling noise. I was thinking B.S. so I had my dad drive me back to the Ford dealer. My dad, the technician, the service manager, and myself all got in my car, and as soon as we drove off, the loud rattling appeared. The technician said the baffles in the catalytic converter were broken. The service manager ordered a new catalytic converter, and said it would be installed the following week. I dropped my car off the following week to get the new catalytic converter installed. A few hours after dropping my car off, they said my car was ready. I picked it up, drove it around town, and the rattling noise was back! I immediately pulled over at the nearest gas station and looked under my car. The catalytic converter was very dirty and a little rusty, which made me think it was the same old catalytic converter. I went back to the dealer and told them my car was still rattling, and they didn't believe me. I had the service manager come outside, and he started my car up and started revving it really hard up to 4,000 in neutral, and then he put it in drive at started revving it to 2,500! I know this is bad to do, and I told him to stop! Within a few moments, I started to smell a terrible smell. I had a feeling it was my transmission, but he said it was the new catalytic converter. After he abused my car, he said it was a loose heat shield making the noise. He set up another appointment for this upcoming Wednesday to fix the heat shield. What do you all think? Are they lying about replacing the catalytic converter? Do they abuse our cars like this when we are not there? What should I do?