Wow, bad news. I have worked in the hospitatlity industry for 10 years and my guess is that the hotel sells so many rooms to each tour operator and Sunwing has used up their allotement. As time goes on other tour operators can release their alloted rooms back to the hotel to put into their inventory, but this may not happen until a month or two before your departure. Are you using a TA? If so I would speak with them ASAP to find out what other options you have available.