@kermit that is a disappointing result. Now you know THS won’t act further your only recourse is to reply to their review in a balanced and unemotional way. Mention some of those petty reasons they’ve given compared to the care you gave. Express your shock and disappointment. If your other reviews are consistantly great I do believe most HOs will read between the lines and see the truth. And sitters cross referencing will get the impression that these hosts are tricky and they will avoid them.
I’m sorry you had this experience. Don’t give up housesitting. I’m sure every sitter (and host) has had at least one horror sit or a disappointing unfair review. Unfortunately its part of the game. I wish you the best.