Dont be so quick to blame. Is the new problem even related to what was done previous?

Eg last week I spent 2 days and 200 replumbing my brakes, then 3 days later the water pump started leaking. Leading to 3 hours of repair between 2 12 hour shifts.

Issues unrelated, but ffffffffff

The new problem is the same exact problem, which they failed to fix. Same warning lights, same symptoms, a week later.

Fair enough :3 What are the symptoms if you don't mind me asking

Check engine light and transaxle light, really hard gear shifting.

Got the car in today and found out what the problem was. A squirrel decided that on top of my transmission was a warm place to spend the night, and it decided that the wires leading to the newly-replaced sensors looked tasty. So, it undid the repairs. Fortunately, the repairs amounted to putting on a new $8 connector, and the car's ready to go again (so I hear, I haven't been able to go pick it back up yet. No longer mad at the mechanic, but there will be an imminent squirrel hunt.

OH GOD Ive found mice nests in my air filter before (plugging it near solid) but this one is new. Glad it wasnt a big problem :3

Most animals hate citronella if you want to spritz your harnesses when you pick it up XD