We are in the business of insurance restoration. We have a client that owes us, per our contract, almost $21,000. He has paid us the total of the original claim amount, but we negotiated with the insurance company on a much larger settlement to cover all of the damages. He won't pay the rest, stating that "we shouldn't know the total from insurance - it's not our business". We have his written permission to negotiate directly with insurance for the settlement, so of course we know the amount. What do we do?