In the end everything worked out... but this was still a pain.
A few years ago I had booked awards travel for a weekend trip meeting some friends (and my then long distance girlfriend) in Vegas. The planned trip was BTR -> DFW -> LAS. On top of that, I got super lucky and they let me book a 1st class seat for DFW-LAS with the normal economy points! I was living large....but that's not what happened.
That was the weekend in early December (2013 maybe?) that DFW had completely shut down for an ice storm. All flights were cancelled and the only way for me to get to LAS on Friday night was to fly United and depart from MSY. First I tried making this change over the phone, but of course that was impossible, American had already rebooked me for the next day. Being a weekend trip this was a tad unacceptable if there was truly another way.
As always with air travel, everything is possible (and free) if you do it at the airport check-in counter. So I drove BTR (20 miles Northwest of my house), negotiated the flight out of MSY, drove the 80 miles back the other way to New Orleans (and right past my house again) to get catch my new flight. I make it to Vegas ok that night, except that instead of a "free" 1st class ticket I sat middle-seat last row from IAH-LAS.
One thing left to fix was the return flight, it was still booked back into BTR, where I no longer had my vehicle. After a little pleading, American actually did rebook me (without the fee!!) to go LAS->DFW->MSY. Unfortunately, that Sunday the DFW still wasn't back up to speed, so American pushed my flight back to Monday. No big deal, I'll spend the extra day in Vegas.
Monday comes around and DFW still isn't up to speed, so I get auto re-booked on United. I was re-booked LAS->IAH->BTR (Same problem, vehicle was at MSY) Tried to fix it over the phone, but they "couldn't do it". So, back to the airport I go to plead my case to the check-in counter.