Car moves in park! Halft shaft and sway bar replaced.

1998 Honda Accord 6 cyl Automatic 160000 miles

I had originally taken my car in for an oil change and for them to see why when I start up my car it makes noise and stutters. They looked at everything and told me that two "fan belts" needed to be adjusted and that they also noticed I need a new "half shaft" and a "sway bar". So I left them do the work along with some other minor things (new rotars etc.) All in all cost me $700. When I left the shop and got home I noticed smoke and a burning smell coming from underneath my car. I called and they told me to bring it back in the morning. I did, and on the way there while I was stopped to make a left turn, I hit the gas and it started to take off and immediately just stopped. I pushed the gas again and it just revved. I went to put the car in park because it wouldn't move in drive and it made this loud EEERRR noise. So I put it in neutral and pushed it to the side of the road. Then I put it in park and shut it off immediately.(It still made the ERRR noise) Popped the hood and the car started to roll towards me!
The car shop told me they put the wrong shaft on my car that it "wasnt long enough". Could they have messed up my transmission?