Okay, so my dad and I were on our to LA when our Audi A6 broke down twice on the way there. The first time was at an exit where it suddenly shut off for no apparent reason. The second time was after making a short stop, driving towards the freeway, when the car suddenly started to lose power. Our car constantly tried to keep up by trying to provide more power to the engine as the power went down and down. As it went lower the engine would start to shake the car. The car once again stopped. We turned it on and drove to the nearest parking lot where it fully gave up and shut off. We tried to turn it on over and over but the same thing would always happen. It would start, then lose power then fully shut off. If you tried to sustain its power by putting it in drive or reverse, it would stay on but wouldn't have the power to actually move the car. Oh yes, before I forget, we had just repaired and fixed up the whole car for about $2,600. It then returned to the shop. We were told the alternator was not working well so they fixed that. My sister drove the car and had it break down right at the end of a busy freeway exit. She caused traffic while trying to turn it on for almost 10 minutes. Again it was returned to the shop.This upcoming Friday we are going to LA as a postpone of the incident that happened a week before. They are still currently repairing and had found out that the key was causing a problem because it was old a worn out. They need to replace it for about $200. We are starting to lack trust for the repair shop so I need help or guesses on what may be happening. I'm sorry this is so long I just need to explain the whole story. Thank you, and I am looking forward to your replies.

-Eyejey