When hosts let you down 2 weeks before coming !

Hey everyone,
My hosts just let me down for july because family are coming to visit them.
I have already bough a few weeks ago a plane ticket to Dublin on July 7th and may not be paid back. I have prepared and bought everything for my trip and now they told me they cannot received me two weeks before coming !
Plus, they didn't write me back when i sent them a message to say that i had bought my return ticket and gave them the dates of my trip which is not very reassuring.
They replied the first time to say that they would like me to come to them and told me about the work and how i can get there. Then no responses and then "sorry we cannot accomodate you!".
This shouldn't happen and i am very mad !!
Elodie