It may be possible to script the negotiations. "Hi my name is X. My friend pointer out that <provider with a good deal> offers <good deal on a detail of the contract>, can you offer anything to reward my loyalty to your brand?"
The phone operators at the other end would most likely be equally unskilled, with set concessions they can make to customers.
Users would have to share their authentication details with the negotiator, which would be a security risk but would mean the negotiator would be indistinguishable from the user.
The service providers certainly wouldn't like it but I'm not sure there's much they can do.
http://news.ycombinator.com/item?id=1228560