The bank is within their rights to hold you to the contract you signed, because the bank was not a party to the divorce. You will have to address this with the divorce court. The judge could hold your wife in contempt, issue a fine, or even order the car be returned to you until she refinances it.
You may be in technical default on the car loan, if ownership changed without the lender's permission. Your nuclear option would be to tell the bank to repossess the car. I would not do this without your attorney's advice, it is likely to piss of the judge. Take the problem to the judge and get the judge to order your ex to comply or else.