For the record, I also received the same “welcome to Ambassador service” and new Ambassador introduction email despite obviously already having my amazing Ambassador. (I actually recognized the name of this new Ambassador as one who sometimes responded to me from the general Ambassador team whenever my Ambassador was unavailable.)
I emailed her back to clarify that I already have an Ambassador. I had a response in a few minutes apologizing for the obvious error and thanking me for my understanding. She clearly already knows my Ambassador, too.
As another data point on Ambassador locations, she said she’s in St. Thomas, ON, Canada.