Outrageous behaviour on the part of the UA agent. I'd go ahead and write to UA and complain, and include a copy of the faxed itinerary to back up your claim that the changes were not voluntary.
I've always gotten personal responses when I've written WHQ to praise a particular employee, and it goes into their HR record. Your praise should also balance what you have to say about the other agent.
John
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From a kiwi who can fly!