I would call his bluff and tell him you cant be bothered and are considering not going through with the deal. I bet they will be quick to see things right.
If they play the "you signed the deal its too late to back out" thing then remind him the same goes. He signed and now he changing his deal (unless there was a clause in the contract, but you being in Insurance industry, Im sure you read all the fine print )
With the economy as it is, its not worth it to him to loose the sale over a minor cost which he will probably just add to the cost of the next deal he does.