I'm just glad it ended well and that they dumped him in your yard instead of on a back road somewhere. I have this image of him finding his old ball in the bushes and patiently waiting for you to come home, so sweet.
Every profession has its idiots, even the most 'noble'. Sorry about the money but I wouldn't spend any more trying to get it back. Keep warning people, without calling lawsuits on your head. You can PM anyone on this board with names; that would be one way to get the word out.
A woman once adopted a cat from me. She wanted it for her young daughter. When I met her in person, red flags went up, she was very cold, didn't even want to hold the cat! But off they went. A week later she called me screaming that the cat was constantly trying to escape, as if I had cheated her. I was quite worried she would throw him out but to her credit, she brought him back. The contract I have with adopters is that they can bring the cat back for any reason. He eventually went to a lovely home.
PS Just wondering, did Oliver end up with family or friends?