OP you are my new hero now LOL.
Following your lead, I called AT&T and talked to a super nice girl who told me the $100 discount is for new customer only (she did try very hard to research and look for promotions for me before she came up with that conclusion). So I asked to speak to her supervisor, and it turned out to be another super nice person. She first didn't want to honor the request but then somehow changed her mind and said she could slash $100 plus tax but not the $36 upgrade fee. After she's done with that, I asked her again to consider removing the $36 activation fee, and she agreed! She said it's because I am a long time customer, just the opposite of what the previous girl said LOL. Those are credited right into my AT&T bill. It did take me almost 50 minutes on the phone to achieve this LOL, but for $142+ I think it's worth it.