Complaints about airlines refusing to pay refunds for canceled flights during the pandemic soared more than 5,500% over the previous year. Some customers are still trying to fight airlines for refunds, while others, who got credit or vouchers for future travel instead, are finding that those credits may soon expire.

And that's outraging some consumers who as taxpayers came to the rescue of the industry when airlines lost billions during the pandemic.

"It offends me," says Scott Slonim of the Chicago suburb of Mundelein, Ill. He and his wife, Nancy, had planned a special getaway for the end of March 2020.

"We were supposed to fly to Washington, D.C., to reunite with our cousin and his wife, to see the cherry blossoms, which we had never seen," Scott Slonim says.

The couple booked flights on American Airlines well in advance. But about two weeks before they were to leave, in mid-March, as the scope of the growing coronavirus pandemic became apparent, their doctor convinced them that they should not go.

"I am 70 and she is in her 70s, we each have underlying conditions," says the retired attorney.

The pandemic would soon decimate air travel, with the number of people flying plummeting 96% from pre-pandemic levels by mid-April. Airlines slashed their schedules and canceled thousands of flights, but American Airlines had not yet canceled the Slonims' flights, so Scott says he contacted the airline and asked for a refund.

"We got a form response from American Airlines, treating it as a cancellation, saying that we had canceled, which in effect, I guess we had, but ignoring our request for a refund," he says.

There's a reason for that: If the airline cancels your flight, federal regulations them to refund your airfare, but if you cancel, you could be out of luck. American did eventually cancel the Slonims' flights to and from Washington, D.C., but because the Slonims canceled first, technically, they are not due for a refund.

So Slonim says he reached out to the company again.

"We started our trip through the American Airlines internal bureaucracy to get to a human being, and ultimately, they responded by saying well, we could have a credit," he says. "Which is like giving us a wooden nickel."

They appealed to American again, in writing and by phone, and to consumer groups for help. They even filed a complaint with the U.S. Department of Transportation, to no avail.

A spokeswoman for American says the airline is providing customers with additional flexibility to make sure those who want to change their travel plans have plenty of options to do so, and American has now extended the time to use flight credits through the end of March 2022. The airline has also eliminated most change fees for domestic and international flights.

But given their age and health conditions, the Slonims say they have no intention of flying again anytime soon, and they feared they will lose the $1,300 they spent on the tickets.

After being contacted by NPR, the airline reviewed the details of the Slonims' case, and the spokeswoman says they now will refund the Slonims' airfare.

The Slonims are not alone in feeling like they're getting the runaround, or worse, from the airlines.

The U.S. Department of Transportation has been flooded with more than 90,000 such complaints since March of last year. That's 57 times more complaints than the 1,500 filed in 2019.

"I will tell you that I have never seen a single issue generate so much consumer anger," says Bill McGee, aviation adviser and a longtime consumer advocate with Consumer Reports. "It's off the charts and this has been going on now for 14 months."

"The airlines have acted reprehensibly since Day 1 on this issue," he says.

McGee estimates that the airlines are sitting on $10 billion to $15 billion that they should refund customers, and adding insult to injury, he says, is the fact that airlines got billions in federal funding to keep them afloat.

"That was given by taxpayers, not once, not twice, but three times, without any givebacks to consumers," McGee says.

But the industry group Airlines for America says its seven member airlines already refunded nearly $13 billion to customers even while hemorrhaging cash at a rate of $100 million a day last year. A spokeswoman tells NPR that those refunds amounted to almost 20% of operating revenue last year, in addition to the billions of dollars of travel credits they issued to customers.

But there's a problem with those travel credits and vouchers for future travel, too.

"Those vouchers are absolutely coming due right now," says Melanie Lieberman, travel editor at The Points Guy travel website.

She says many airlines are extending the expiration dates for those travel credits to later this year or well into 2022, but she notes that getting an extension instead of having the credit expire may depend on when you bought your ticket and when you planned to travel. And Lieberman says every airline's policy is different.

"The best thing you can do is go double-check those dates, make sure you know the fine print, the details of when your voucher needs to be used and when your travel needs to be booked by," Lieberman says.

Sens. Richard Blumenthal, D-Conn., and Edward Markey, D-Mass., are calling on the airlines to offer cash refunds instead of credit for flights canceled during the pandemic and to eliminate expiration dates for travel vouchers. They say they will propose legislation that would force the airlines to do both.

The Department of Transportation has issued two enforcement notices in the past year reminding airlines and ticket agents of their obligation to provide refunds for canceled flights, and the agency this week updated its guidance for consumers who believe they are owed a refund.

A DOT spokesperson says investigations into the the enormous number of complaints continue but adds that "thousands of passengers who had initially been denied refunds have received or are receiving the required refunds."

Meanwhile, while complaints about denied refunds for trips they could not take skyrocketed last year, a new survey of those who did fly, finds that airline customer satisfaction during the pandemic hit an all-time high.

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