Time to dispute was as soon as you got the ticket. If you think it was wrong demand it be sent in for federal grade. You will have to pay for it and accept whatever they deem it as. Terminal will probably balk and try and do everything they can to discourage you from doing this. Hold firm and demand it be sent for federal grade. Don't bother calling, make the drive to the terminal. Show up in person and demand that sample be sent for federal grade. | 
How do you protest a grain test at river terminal?
