Best to officially chase it up via the Tour Operator/Travel Agent you booked with stating that you specifically booked the complex due to the open restaurant policy. They will be the ones you will be seeking compensation from when you come back if it is not the case.
We ate at the Coba "restaurants" every evening bar a trip to the "oriental" in the Hacienda, which is a shared area, and a trip to the "turtle" restaurant at the Tulum, which was the only steak house we found.
Quite a few "cross hotel" people were using the Tulum and Akumel snack bars at lunch time, but the only time my daughter did she was ill for 24 hours. We kept away just in case and went back to the Coba if we felt peckish.
At the Coba, there were restaurants we could not use as we had not upgraded to premium class or whatever it was, but the loss of facility was not even noticed, in fact I had even forgot they existed until this brought it back to mind.
They may well be trying something like this:
I have mentioned elsewhere that we were unable to book the steakhouse at the Coba because according to Customer Services there wasn't one, as far as they were concerned no restaurants existed outside the Coba/Hacienda complex, however when we arrived back at the customer services a couple of days later and stated we wanted to book the Turgesa, it was accomplished immediately and with no fuss.