What type of lawsuit should I file? Small claims or civil lawsuit. And do I have to a have a lawyer represent me?

I live in TN and I paid a repair shop to repair collision damage to my SUV. Some of the things they charged me for were not repaired/replaced at all, and some things were repaired improperly. (Ex. They mounted and secured my front bumper using plastic zip ties and they didn't repair/replace the damaged reinforcement rebar, but they charged me for the parts and labor for it). Anything could have happened to myself or my children while driving because of their shoddy work. I have confronted them, filed complaints with the BBB, consumer complaints, and a complaint with the FTC, but still no resolution. A lawsuit is my final resort to collect my money back.