AFAIK, while the Airbnb Avios deal has its own page on ba.com, it's really just the BA eStore behind the scenes - and therefore, the randomly and inexplicably refused Avios, impenetrable customer support, and other BAEC teams not knowing what to do with you, are all par for the course. Prior art: 1, 2, 3

I definitely understand and share your frustration. But the unfortunate reality is that I don't think you'll ever receive your Avios.