Did you try Red Heifer?
Sorry, I was asking others that were there. I read the TR and it was awesome. I'm going next month and it was very informative.
See here on the Cancun map I created (it's in the Cancun wiki for future reference). There are 2 Haagen Dazs locations. I went to the more-northern one, near the Hyatt Ziva.
Did you try eating at the restaurants on site? Were they accommodating at all towards kosher?
I did not, except for breakfast in the lobby/lounge which I described above as having kosher cereal.