Thanks for the address, but any letter we would send would be dismissed as second-hand info, and not taken seriously.
Anyone could send a letter to them, and say, "I heard from a friend and they said...." The chance to hurt someone's career would be too easy for any random person to send such a letter (perhaps even a co-worker!), and since direct contact with the person who was actually hurt is impossible, management (of any large operation) won't follow up.
It's your choice, of course. I'm glad it worked out for you to go to another office.
🙂