Airbnb host wouldn’t accept reservation change [Australia]

I originally had a booking for Feb 13-Feb 25 and I sent a request today to check out tomorrow Feb 18. The stay was fine, if anything I think the home is a bit dusty and my allergies have been acting up but not something I would raise alarms over, it’s a personal thing. I didn’t mention this to my host.

The request was denied by my host because it’s very short notice and they can’t get another reservation in. They would discuss refunding the last two nights of my original dates instead.

I’ve reached out to Airbnb for support because I’ve never changed or cancelled a reservation before so I’m not sure if I’ve gone about this the wrong way? I understand it’s short notice and it’s up to the host to accept/deny my request but what should I do now? There’s a cancellation policy where I’d get a partial refund for all the nights remaining in my reservation, so would I just opt for that?