I've read on this board about this problem and have seen ways mentioned about getting around it. Of course, I can't remember them. I did a search on "Punta Cana" and found this thread. I did not re-read it to see whether it has the info you seek, but enjoy the read. Other threads also were found which may have your answer.
http://www.massageplanet.com/forum/showthread.php?175707-DR-Trip-2011-The-Adventure-Continues!&highlight=Punta+Cana