I've tried this twice - once with the Westin Georgetown and once with the Sheraton Iguazu. Asked for the revenue manager by calling the hotel directly both times. The RM at the Westin Georgetown opened up inventory on two of the four nights that I wanted (the other two already had C+P). The RM at the Iguazu Sheraton was of no help even though I'm quite sure the occupancy at the time we were there was low enough that his reimbursement from Starwood would have been the same under C+P or full points. Maybe something was lost in translation and he didn't understand my request.