I would have to be the party that was guilty on insinuating that.  If they were that wonderful of a firm they would have at least given the client a hint that they would need to amend some returns.  And how did the client end up down there to begin with?  Did the firm go on a fishing trip looking for new fish to catch by contacting the client and telling them that they were going to be able to save them a billion dollars through their great skill and knowledge?  Taking a percentage of the payoff should be left to ambulance chasing lawyers, not CPAs.