When Chu Lisong Chang and her husband arrived at the Vancouver airport on June 24 to take their Sunwing flight to Toronto, they were shocked to discover that the plane had already left — four hours earlier.

Desperate to return home to Toronto, the couple paid $1,309 for two last-minute seats on an Air Canada flight. It didn't depart until the next morning, so they spent the night in the airport terminal.

"It was horrible," said Chang.

She had never received a notification that her flight had been rescheduled, but when she confronted Sunwing and her online travel agency, FlightHub, neither company accepted any responsibility.

"It's their fault but they're blaming us," she said. "What can we do?"

Chu Lisong Chang of Toronto enjoyed her trip out west — until she arrived at the Vancouver airport to fly home and discovered she had missed her flight. (Submitted by Chu Lisong Chang)

Chang is one of two Sunwing passengers who complained to CBC News last month that they missed their flight — booked using FlightHub — because they didn't get a flight change notification.

At the time, both FlightHub and Sunwing wouldn't accept any blame or offer refunds.

However, following a CBC News investigation, Sunwing reversed its stance and offered to reimburse both customers. The airline said that although it had followed proper procedure, it was discovered that the passengers had never actually received their flight change information.

Despite this revelation, neither Sunwing nor FlightHub has admitted any fault. Even so, the passengers are relieved they're getting their money back.

"I've waited so long," said Chang, who will be reimbursed for her Air Canada tickets. "I'm feeling quite happy now with a little justice."

Feeling 'powerless'

When Chang initially tried to get answers in late June, she hit a brick wall. She said Sunwing insisted it had sent FlightHub her flight change information.

Chang said FlightHub told her it had forwarded her the information, so it was her fault she missed the flight.

"They just washed their hands of [it]."

Rolland Li of Vancouver endured a similar experience. His troubles began when he and his fiancée, Hannah Ng, arrived at the Vancouver airport on June 28, and discovered their Sunwing flight to Toronto — booked using FlightHub — had been cancelled.

Unable to afford pricey, last-minute tickets, the couple had no choice but to forgo their trip to visit Li's parents.

"I felt horrible," said Li. "When we got home, I honestly just started crying because I only get to see my family once or twice a year."

Not only did Li never receive a notification about his cancelled flight, but also, he was never alerted that Sunwing had actually rebooked the couple on an Air Canada flight for the same dates.

On top of that, neither Sunwing nor FlightHub would refund the couple's Sunwing tickets — which cost $996.

"I just felt simply powerless," said Li. "If the airline doesn't want to do anything, and then the flight agency I dealt with doesn't want to do anything, it just kind of seemed like I was out of options."

'We made best efforts'

When CBC News first asked Sunwing about Li's and Chang's cases, the airline said that it had done its job by notifying FlightHub about the passengers' flight changes.

FlightHub said it had passed on the notifications to the passengers.

However, several days later, Sunwing sent Li an apologetic email and offered him a refund.

Following a CBC News investigation, Sunwing has decided to reimburse two customers who missed their flights because they didn't get notification about a schedule change. (Christopher Katsarov/The Canadian Press)

CBC News reached out again to Sunwing. The airline said that it had had "another opportunity" to review both cases and had determined that Li and Chang weren't at fault.

The airline said that although it had sent the correct information about the flight changes to FlightHub, somehow the passengers never received it.

"While we maintain we made best efforts to advise our customers of these changes and did advocate on their behalf with their travel agency, we appreciate that their travel plans were compromised and sincerely regret the inconvenience they experienced," said spokesperson, Rachel Goldrick.

When asked for comment, FlightHub suggested Sunwing was to blame, claiming the airline didn't properly enter the flight changes into a shared software system.

"Sunwing did not send the changes through," said Nick Hart, CFO of Montreal-based Momentum Ventures, which owns FlightHub.

Sunwing denied the accusation.

What are the rules?

While it could not comment on these specific cases, the Canadian Transportation Agency (CTA) told CBC News that, in general, airlines are responsible for advising passengers of flight changes and cancellations.

Canada's new air passenger regulations — which took effect a few weeks after these Sunwing cases — state that airlines must keep passengers informed about flight delays and cancellations.

Passengers who feel they weren't provided with adequate notifications can file a complaint with the CTA.