Can I sue the company for not doing my transmission job right even after 4 times returning my car to have it fixed?

I took my car for transmission work. Got it back, 2 days later there was a shifting problem. Send it back and paid $80 out of my own pocket for a rental car even though I feel they should have paid since they were the ones who couldn't do the job right in the first place. Got it back, a few days later the same exact shifting problem, so I send it back again. This time since they kept it longer the rental bill was $820, again out of my pocket. Got the car back and this time the car did not want to accelerate so I turned it off then on switched from park to drive and the transmission kicked violently. Send it back a 4th time and they tried to have me sign a receipt with lawyer language on it, I refused, saying that I agree to release all liability and won't sue them ha. That happened because I got the BAR involved. I just got my car back 2 days ago and now my car drives horrible and I'm currently stuck in a lot (next to a mechanic shop) because the starter doesn't work. The mechanic next door told me the starter problem had to do with the transmission job since it is intertwined with something else for the transmission. The transmission job cost $4,000. How can I sue them especially when they had their lawyer write up a paper for me to sign stating I will not sue them and release all liability?