general problems of the 2007 Saturn SKY

I purchased a used Saturn Sky 2007 vehicle. July 26th 2016. I noticed immediately the same day as a matter of fact a noise from the back end. I took care back a and they put grease in diferential. . But after a few days it was worse than ever. I purchased the extended warranty plan. After they tried looking at my car. I called my warranty company and ask if they could recommend a service center to take my car to have it serviced. Which I then proceeded to do. And my vehicle is still there. They sent a used diferential that was bad. I asked the warranty representative at that time to send me a new one which my contract states clearly I can have. But once again they sent another bad used one. And then another. Along with two others that were never delivered. And I've been offered a rental for 8 days total. And it is now oct 18th. 2016. I have no car. Gm has this part now on national back order. And does not know when a part will be available. I attempted to contact different machine shops to see if it can be rebuilt they have tried to find parts to rebuild it there are none. I feel I have done everything possible to fix this vehicle. And it's a lemon.

After I parked my Saturn Sky in my daughter-in-law's driveway for approximately 15 minutes, my son-in-law and I heard a loud "pop" from my Saturn Sky. About 5 minutes later, my Saturn Sky drifted backwards out of the driveway (slight downhill direction) and into the street. My son-in-law ran after the car and caught up to it just as stopped drifting backwards uphill in the street and began drifting forward in a downhill direction. He was able to reach into the car (the convertible top was down) and set the emergency brake. While doing so, the car ran over his foot injuring his toe. Thank god there were no children playing in the driveway! the emergency brake was initially set since the driveway does have a slight slope towards the street, but after cooling down for approximately 15 minutes, the emergency brake released.