We just got Sunwing to change our oct.11th trip to holguin to a five star in punta cana. We didn't have trip insurance and our travel agent we just had to sit and wait. Contacted sunwing directly and they let us purchase trip insurance retroactively at $49.oo p/person and then cancel our Holguin trip, giving us a credit. We used that to book a trip at another resort of our choosing. They were very accomodating even though our travel agent wasn't even willing to try to work anything out until the final word was in on how badly damaged the resorts in cuba were. We did not want to go to a resort under construction after the hurricane and did not feel right about being served by people who had just lost their homes.
Anyway, if you want to make a change don't be bullied by your travel agent. Beat the rush and book where you want because Sunwing is willing (so far) to deal with you.