[Cautela]

I'm home on vacation and my mom is having problems with her CL's automatic transmission, I would help her out with it but unfortunately I don't know much about transmissions. The car was taken to the mechanic twice already and over $700 have been spent trying to fix it, here is the situation: About two years ago my mom claims that during an argument my sister put the car in "park" while the car was in motion, I thought that was not possible but I wasn't there so I cannot deny that's what actually hapened. Recently the car started making a rattling noise and when my mother took it to the mechanic they told her that it was the bearings in the differential (I asume she means the LSD) and the piece that holds all the bearings was bent and broken (I actually saw it) and they replaced it and the mechanic "raised the pressure", now the car is jumping agressively when it shifts, this happens when the car is driven cold and it's not as bad when it warms up, also it revs up and it doesn't shift until about 3 seconds after applying the gas, this is also mostly when cold, but could this have nothing to do with the LSD?. My mom is taking it to the mechanic again tomorrow but she's not gonna let them charge her for it so they may not do anything to fix it, I'd appreciate any help from the people that know anything about this.