There is an old fashion device available almost everywhere (maybe even in your pocket) called a telephone!! Just take the local and 800 number and call at least twice a day.

I too am so pre-programmed doing everything online that calling and talking to another human almost seems frightening - I fear reaching an incompetent who Yeses or No's you do death just to get you off the phone - honestly as a CPA, I too would rather leave simple clerical details like these to a machine with an audit trail.

And I've never, ever gotten a callback from a Marriott hotel when leaving my name/number "in case something opens up" And that includes when I was already staying on site looking to extend! Alway had to ask again and again each morning...

But it seems like you have to go this route. As someone who has done a lot of sports team booking, it is very probable this will open up last minute although you might not like the rate.

Best of luck with your trip and parents.