Update:
My niece is a slug.
Okay, I called her this morning which was actually afternoon there and she hadn't left the house yet. I phoned the vet and they don't have a phone number either but I managed to get her to give me the address which is on the SAME STREET as my niece. My niece claims to have knocked on doors yesterday but... not sure I'm buying it. She thinks they are at work. She did give the poor baby a bath as he was pretty dirty, she thinks maybe he's been outside a few days. He did look pretty scraggily but I'm thinking he must have dug under the fence or something. I told her to let me know as soon as she's gone down there but no word yet. Told her to try again tonight if they weren't home this afternoon.
The thing that bothers me is no phone number anywhere...... why would you not? Anyway, I'll keep you posted. I've had several offers to go pick him up, thanks to all who volunteered, I feel better knowing I can get him to someone if it comes to it.