What does your attorney say? Mine was happy to sue creditors where damages could be recovered, on a contingent fee basis. If you're saying the repoed three days early because the discharge wasn't granted until the 4th, that's probably the creditor being aggressive but not a big damage award.
from being in the repo business for many years, its not an illegal repo to repossess a car involved in a bk unless you make contact with the debtor. I personally repossesed many vehicles that were involved with chapter 7's.
The original post is a bit unclear, apparently the lender filed to lift the stay, if the stay was lifted it's not illegal. I believe the discharge on 9/4 ended the stay. So if their motion to lift the stay wasn't granted the repo might have been three days early and technically illegal, but unlikely to draw any useful sanction.
One of the best possible outcomes of a bad situation. Now that you've got that behind you. Time to pick yourself up and start rebuilding. Good Luck!