As a new SPG Platinum this year, I'm confused on the Guaranteed Availability benefit. I need to book a room in Tampa at the end of August, which is apparently the week of the Republican Convention. So I just had the following conversation with the Platinum Concierge line:

SPG Plat Agent: "Thanks for calling the Plat line, how can I help you?"
Me: "I need to use the Platinum Guaranteed Availalbilty to book a room at the Tampa SHeraton on August 26-30."
SPG Plat Agent: "I'm sorry, there's no availability that week."
Me: "I realize that which is why I'm calling to use the Guaranteed Availabilty."
SPG Plat Agent: "I'm sorry, the system won't let me overide because it doesn't meet the minimum requirement."
Me: "I don't know what that means, but I do know what 'Guaranteed' means, so I'm not seeing how this is not possible. Please tell me what I'm missing here."
SPG Plat Agent: "Let me call the hotel and see why I can't overide this. Please hold"... ... ... "I just spoke to the hotel and they are completely sold out and have been for months. In fact, she also told me that every hotel in town is sold out that week."
Me: "Uh, okay. Thanks for your help."

Can anyone explain how this is supposed to work?