Revs high and won't go into gear

I just bought a 1996 Dodge Stratus 4dr. Auto about a week ago and have had to get it worked on. Today, the same problem that was supposed to have been fixed got worse. The car revs high and the rpms won't go down sometimes. The shop said that they didn't have any problems with the way it shifted or revved, however they changed the transmission fluid/filter and had to reset the computer, that was yesterday. Today it wouldn't down shift at about 4000rpms so I slowed to a stop and restarted it. It went about another 1/2 mile doing the same thing, this time it wouldn't go in gear, not reverse or drive and it only would go into neutral if the key was off. I had to tow it to my house and here it sits.