My dog got thrown out of obedience class?

My dog is 3 year old GSD named Bruce. This is the third time that he has got kicked out of an obedience class. The trainer said that he is very impulsive and a bad influence on other dogs. I even had a trainer to look after him personally but even she couldn't help. I've tried training him at home but he just never listened to me even as a puppy. What should I do?