Did you make the cruise booking for each of you and in the same phone call? Or did each of you make your own booking separately? All the different promotions and booking categories can be very confusing. If each of your bookings were made separately, then you could have been booked under a different fare code promotion. It's hard to determine without actually seeing the booking confirmations. Probably the best thing to do is write a polite letter to Guest Relations asking for them to explain.