Sounds to me like someone either doesn't like you or doesn't like your dog's breed, and is hoping they take her and deem her a dangerous dog because of her breed. So wrong.
I agree with Ali.
It sucks thugh, I was going to suggest calling the RSPCA yourself but i dont think they can tell you anything anyway with privacy laws etc.

FWIW on the radio Dr Hugh Wirth said anyone who goes on holidays and gets someone to feed their dog while they are away is guilty of neglect?!!