My son had this (accept, then try to get him to cancel by never communicating nor picking him up) happen to him before a flight out of SD. He almost missed the flight. I just deleted the Uber app from my phone.
I've never used Uber, so I'm curious: Don't you have a "contact support for this ride" option somewhere? If they can't mediate a two-sided market, they're no better than having a phonebook of recommended drivers in each city
Yes, there is a support option in app w/ chat support. It's generally unhelpful, and you have to be extremely demanding to get them to take any action at all. The "support" for Uber is basically designed to tell you to f-off as politely as possible.