I agree to use your agency since I had the same thing happen..but in this case I am the T/A and my customer experienced the exact problem you are having! It may not be something we normally handle but when a cruise line drops the ball, I do think we should pick it up for you. The couple did get their account credited but I do think it was because I got the right person on this occasion.
As a side note, my representative for RCI just listened to me vent about very specific cases where RCI just fails to respond to both customers and travel agents. It is very frustrating and I even told them on a survey that I think they need to trim their advertising budget a bit to fund some more personnel to handle consumer issues. BUT there I go being logical again ;>)