Repossession of an automobile

My husband had his car repossessed last week. His loan is now over12,000 dollars while his car is only worth 3,000 dollars. He never received any notification that they were going to repossess it until after it was already repossessed. I read that the bank must let the car "owner" know that it is going to be reposssessed within 10 days of the repossession. Also, the person who repossessed the car opened our garage looking for the car as my husband's car was parked outside and covered in snow. I read that this is illegal. I just don't know where to go from here. We can't afford to continue paying this enormous loan off. My husband was paying over $400 per month. He contacted Americredit (the bank) to let them know that his money situation changed since taking out the loan, but they refused to work with him to lower the payments so that it's something he can afford.

Can they sue him?
Was it an illegal repossession?
Will he continue to have to pay 400 per month even after the car is auctioned off?
Do we have any options here?

Thank you very much for your time.