transmission

What is your question?

The transmission will shift hard and will start at any time. It doesn't do it all the time, but when it starts it wont stop until you turn the car off and leave it off for about 20 sec. Then you can start the car and it can go a month or 5 min. before it starts doing it again. I had the transmission serviced and they didn't see anything wroung and it didn't do it for about three weeks. I don't know whats wrong with it. Any help would be great. Thanks