Q: Car has power reduction and grinding noise

My car has been shifting rough and I went to the dealership and reported this. I was told that this was normal. I trusted the mechanic and so I went ahead and used my car. A few months later while I was driving in a parking lot, the transmission failed, the engine shut off while the car was moving and I was jerked to a stop abruptly. I went to the dealership and they explained to me that the problem was due to computer errors controlling the transmission. Then three months after that, my car looses a good bit of its power, develops a grinding noise, and the check engine light came on. Fortunately I was only a few blocks from the dealership and managed to get there in my car. There were a number of faults, according to the technicians and they reported these to VW of America to get advice on how to proceed. They eventually decided that part of the transmission called the mechatronics unit needed replacing, but they had no idea of when one would be available. They told me gave the car back to me and told me to drive it until the parts arrived. Really??!! They told me that it was just a noise. I responded with repeating to them about the serious power reduction that had occurred and the previous problem just a few months ago when my car had complete failure of the engine and the transmission. They denied that these two problems could be related. After my complaining to them, they said I could rent a car and I kept complaining until they gave me a loaner. I am thinking that they are using a tactic of which I have read, on how to get around lemon law liability. I am concerned that the real problem isn’t being considered by them. Please give me your assessment of all of this and any advice that you can give.