Bed bug rental

We were moved into a rental that we learned after moving everything into that it was infested with bed bugs. All expenses minus heat treating was covered by us & we submitted the rental rectification for over $2000. They came back and are settling for $500. They also are denying paying for us to replace the master bed where most of the bugs were found because the exterminator did not find “residue” but over 10 alive bugs on our mattress that had been there less that 24 hours.