She sounds incredibly shy to me, and completely lacking in self confidence. Is English her second language? She will sense your disapproval and hide away even more. Fear of wasps is incredibly common, and if she feels uncomfortable in the sun, that is why she keeps her blind down and doesn't want to go out.
I know she is not the sort of carer you were hoping for, perhaps a bright, chatty soul to share cups of tea and a natter with, and perhaps you need to stress your needs to the agency. But the agency telling her she has been rejected again is not going to help her have the confidence to help someone else. Have you actually taken her a drink and piece of cake and really tried kindly to find out what she thinks her role is, and to explain what you were hoping for, and discuss how you could move from one to the other?
My heart goes out to her, she must be so unhappy.