I am so sorry you're having such trouble. I've had nothing but joy with my Pfaff machines - and I have 3. I also have a marvelous dealer who would make it right for me if I had gotten a lemon, which is what it sounds like for you.
As for their newest top of the line machine - the Sensation- I've seen several in use/purchased and each owner seems to be thrilled and has had no trouble that I know of.