2003 Hyundia Accent Transmission Problems

My question isn’t about my car, but instead about my girlfriend’s car named Ozzy. Ozzy is a 2003 Hyundai Accent with an automatic transmission. Over the last 2 year he has been having a lot of problems with his transmission. The first thing that was done was to replace his transmission fluid. Unfortunately the chucklehead that replaced his transmission fluid put the wrong kind in and he had to have a whole new transmission installed. And now only about a year later Ozzy is having transmission problems yet again. What is happening is that it feels like the car is struggling to shift gears and then once in gear it will suddenly accelerate. Also, the idle races even when your foot is not on the gas pedal and yes, the check engine light is on. So, I have a couple of questions. First how much longer can she keep driving it like this before the engine falls out somewhere on the 405? Secondly how much is it going to cost to repair Ozzy? Also her driving the car when it is behaving this way is really dangerous, right? Because it felt pretty scary today when I was sitting in the passenger’s seat and we were doing 75 on the freeway and Ozzy was shaking and making all sorts a noise. And lastly, she needs a new mechanic right, there is no way she should keep going to these guys that put the wrong fluid in and then replaced her transmission with a dud, right?

Thanks for your help,

Driving 75 in a car that is shaking and making bad sounds should be avoided. Get the code that set the Check Engine Light and avoid driving Ozzy whenever possible until the problem can be diagnosed and repaired. Hopefully it is Ozzy Nelson, not Ozzy Ozborn.