How Should I go about this? Do i leave it be or contact an attorney.

I’ve had issues with my car radio for a long time and every time I go change it. This time I didn’t want to but I was hearing a weird noise come from my car when driving so I decided to go to the car shop for that car let’s say Kia. But they said I had “brake issues” which would cost $500+. I paid upfront and got my car back but when I used it the next day it broke down on the middle of the road which I’ve never had happen before. I sent the car back since I legit just got it but now they are telling me the issue lies with my “engine” and they can’t do anything about it, when they already took over $500 from me claiming it was brake issues the day before. What do I do? The car won’t work now and they refuse to fix it and are asking me to come for it. What do I do? Do I contact a lawyer? Or do i just accept this? But I refuse to since it would mean I wasted my money for no reason.