What would you do if you drove your car to a mechanic for repair and after service the car is not drivable

My girlfriend took her car to PEPBOYS to have "ALL" engine mounts changed on a 1999 MERCURY VILLAGER. When they gave her back the car after supposedly had completed the job, the car shut off within a 1/2 mile of the shop. She called me frantically saying "the car is not running right and i don't think i'll make it home or any further. She was stranded. I met her at the scene to see what the problem was and discovered that the exhaust manifold was glowing red. I immediately shut her car off. I left it there and drove my car to PEPBOYS to tell them the problem and to see if it was in their policy to provide towing services in case of these matters. They did but it was a 2 hour wait, so I stopped at the nearest car parts store and bought a tow rope for and pulled her car back to PEPBOYS. They looked it over and claimed that their services were not the cause of the car's problem. So then I asked," What's wrong with the car. Why is it operating so poorly now when it was working fine before any work was done?". Nobody had an answer and i felt helpless and cheated but, since she needed her car, because thats the only car she has. So I had to get a second opinion from a close friend who's a certified auto mechanic. We towed the car from PEPBOYS lot and brought back to her house. My Mechanic friend met us there and found that an important cable that controls the amount of air that flows thru the engine was left loose and the engine mounts were not installed.