As someone who travels frequently, Denise Smith, a San Francisco Bay Area resident, was thrilled to learn this spring about Frontier Airlines' GoWild all-you-can-fly pass.

For a flat fee of $699, the GoWild pass allowed her to fly anywhere — domestic or international — for three months at a time. Smith believed she'd be able to spend those months fulfilling her travel desires.

And initially, she did — taking five trips in April and May.

But suddenly, as June approached, Smith could no longer find any flights. She reached out to Frontier's customer service, who told her to clear her web browser, or even try a different computer.

Finally, Smith said, a Frontier supervisor told her she'd get back to her about what might be amiss — but never did. Smith eventually received an email saying that no flights were available for the destination she had in mind, and that she would have to check no more than 24 hours in advance for openings.

In fact, Frontier says there have been no changes made to how the GoWild pass works. Its critical feature is that passengers are indeed unable to book domestic flights more than 24 hours in advance — though the carrier said it has run early-booking promotions in which the 24-hour window is waived. Passengers can buy international flights up to 10 days before departure.

“Now unfortunately because I’ve purchased that pass and am unable to use, I have to book through regular airlines,” Smith said. “So I’m spending more money than I thought I would when I bought the pass.”

A Frontier spokesperson said the pass is designed for people with almost unlimited freedom, like retirees, remote workers and college students on summer break. These passengers typically have the ability to travel at a moment's notice and don't mind making stops.

Jacob Brown, a teacher who lives in Denver, moderates a Facebook group for GoWild pass holders. As a regular Frontier traveler, he has learned the best tips for flying with the airline and shares advice with the 10,000 members of the group.

“The whole point of the community, I would hope, is that we can help people make the most of it," Brown said, referring to the GoWild pass. "So understanding how to use the pass, places to go, deals when you’re there, how to save on accommodations, stuff like that.”

As a moderator, Brown said he's seen people who think the pass is the "best thing they've ever done" and others who think it's a scam. Brown said much of the frustration comes from a misunderstanding of how flight availability works and how it varies depending on the airport.

Some pass holders might think that Frontier reserves seats for GoWild members, but Brown emphasized that they are paying to access leftover seats for cheap. Others have complained that some flights have tickets for sale and no GoWild availability, but Brown said those flights are being oversold. GoWild tickets are only available if there is a guaranteed seat on the plane.

"It really is unlimited access to empty seats," he said. "But it's also summer, and everyone's going to Disney World and everybody's going to Vegas and so the flights were already fairly full. This is not the slow season for air travel. So it's going to be difficult to use the pass if you're trying to go somewhere that everyone else is trying to go to."

Denver is one of Frontier's hub airports, so there are more options for flights and destinations. Brown has flown to Dallas, San Francisco, Missouri and Pensacola, Florida, using the pass. He said he has already made his money back in savings.

However, for others who don't live near hubs like Denver, Las Vegas or Orlando, Florida, finding options can be difficult. Michael Mastronardi, a video producer based in Orange County, California, posted a TikTok sharing his frustration trying to book an international trip with the GoWild pass from the John Wayne Airport in Santa Ana, California.

"It was just a huge headache, trying to navigate everything," he said.

Mastronardi told NBC News he and his girlfriend eventually booked a trip to Nassau, Bahamas. On the way, they will have two overnight stops in Las Vegas and Orlando, and on the way back, they will stop overnight in Orlando and land in Philadelphia.

From Philadelphia, Mastronardi said, "it'll just be day-to-day checking" for flights back to Santa Ana since domestic flights can only be booked 24 hours ahead.

Mastronardi said he's not seeing the same functionality with the pass as others are, which he understood was partly because of his location. Frontier has three available routes from the John Wayne Airport, according to its website.

"At this point, I'm wishing that I didn't have it. I would have much rather just had the money in my pocket to spend," he said. "Essentially, I sacrificed my control over my vacations for the ability to book these flights for like slightly cheaper."

Even pass holders who enjoy the pass admit that they have to relinquish some control of their trips to get value out of this pass. Brad Nelson, a software developer based in San Francisco, said he had to get over this gripe when he first started using the pass.

When he initially traveled with it, Nelson said he would get frustrated because the flights he wanted weren't available. However, he came to accept that if what he initially wanted wasn't available, there was always another option.

"If you have some flexibility, you can totally get there and back," Nelson said. "It's just part of the game of finding which flights are available."

Nelson noticed that finding the full list of flight options online for GoWild pass holders was time consuming and difficult, which fueled a lot of the frustrations with Frontier.

As a result, Nelson created a text service that allows people to find all available options for flights departing a specific airport, which he said over 1,000 people have used so far. He is currently building a website called the 1491 Club that will have more search tools based on feedback from members of the GoWild pass holder Facebook group.

"It's turned into a more positive experience because people are realizing that there is value in the pass," Nelson said. "It just was previously hard to find."

He added, "The point of being a budget airline is these resources are not going to be given to you. But as a group, we're figuring out perhaps without those resources, if we work together, we can still utilize this pass."

Smith, from the Bay Area, still feels deceived.