I recently had a similar situation, though not of the same magnitude, with Amex and United. Amex was no help, but United came through.
Four of us will be traveling SFO-BOS on tickets bought with Amex Biz Plat. There is a schedule change of 20 minutes on the departure and 45 minutes on the arrival time...bringing us back to BOS 45 minutes later than originally promised.
I called United, and they originally told me that they can't touch the ticket and that I had to call my TA. I contact Amex, and they said that the schedule change was not significant enough to satisfy UA's criteria for change without penalty (said it was 2 hours). Amex said sorry but can't help you. I called back UA and explained the situation, told them that my TA, Amex, was totally unhelpful, and appealed to UA to provide excellent customer service. The agent talked to his manager and went ahead and made the change for me, putting us on an earlier flight, with no change fees. Really nice to see UA step up.