There are a few things here I don't understand. First, if you have a cruise planner, have you tried to contact this person and inquire? Also, when your group coordinator didn't get back to you, why didn't you follow up and contact him or her again? Did you try speaking to the Pursers desk about your refund? Why do you say RCI refuses to discuss it, have you called their customer service department?
Just curious, what other activities do you think RCI should've provided when the ship missed Coco Cay? If you read the "Contract of Carriage", you will see that the cruiseline can alter an itinerary for just cause, like weather. I've been to Coco Cay many times, and the BBQ is really nothing more than some burgers, hot dogs, chicken and ribs made in a kitchen and brought out to the food islands in metal trays for the passengers to pick through and eat, almost exactly the same as you would get in the Windjammer Cafe. If you thought they'd be BBQing a pig on the beach, that just doesn't happen. I don't mean to diminish your disappointment in any way, Coco cay is a wonderful island and a great port-of-call. However, I'm sure that while the ship didn't add on any other activities, all the regular ship's activities were intact and the Windjammer, dining room and pool were open.