OP here to follow up. Had a much better agent today who re-accommodated me to keep lie flat seating. She had to get approval, was on hold for along time, she came back on and maybe she gave up saying "I've approved it myself." She seemed knowledgeable, so I mentioned the Contract of Carriage says seat type will be protected, she said it's not really guaranteed but that most agents will try to work it out if there is room to do so. She did. Agent and supervisor last night did not.