 canceling hundreds of flights today on top of the roughly 1,300 for each of the three previous days, about a third of its scheduled flights. The Atlanta-based carrier, which was the worst affected, has also delayed thousands of flights since Friday. Secretary Buttigieg warning that the carrier must provide its customers with adequate assistance and refunds, but some stranded travelers posting cell phone images to social media showing how they couldn't even reach customer service with hold times of seven hours and counting.