You may be right....
B.WHOLLY UNUSED NONREFUNDABLE TICKET POLICY.
A WHOLLY UNUSED NONRFND TKT MAY BE APPLIED TOWARDS THE PURCHASE OF A NW/KL DOMESTIC/ INTERNATIONAL FARE/TICKET. -PROVIDED TRAVEL ON THE NEW TICKET ORIGINATES WITHIN 1 YEAR OF THE ORIGINAL OUTBOUND TRAVEL DATE AND THE TICKET IS EXCHANGED NO LATER THEN 365 DAYS AFTER THE ORIGINALLY TICKETED OUTBOUND TRAVEL DATE.
Keep calling until you get an agent who can help you. Try to make it during the day in the USA when more experienced CS agents are working. Maybe that will help.