After weeks of calling and checking online for my room type to open up on a newly added date... and getting the same response, sorry, there are no rooms available for your room type.
I decided to contact Guest Services. My rationale was..."I know there isn't any available because I am holding one of the spots! There has to be somebody that can override the system and not have check availability the same way we do online (cancel and rebook process).
I was so blessed to be contact by a GS-CM and she added the extra date, cancelled my room only (I had previously booked, JIC) and updated all my DME information... and she only had my name, state and month!! She didn't need any other info, like er.. my reservation number. I couldn't stop thanking her.
We are sooo happy! Finally!!
Coincidently, I check online to see if there was any availability for my room type for the extended dates online and NOPE. The CM really did pull out her magical GS pixie dust.