Some WestJet passengers are crying foul after getting hit with a $30 checked bag fee charged in U.S. dollars.

"This is a pretty sneaky and dirty way to squeeze extra money out of your customers," said Taryn Zielke who recently had to pay the fee.

On Aug. 28, WestJet began charging baggage fees in U.S. dollars for return flights from the U.S., Latin America and the Caribbean.

Many passengers started noticing after Oct. 1, when WestJet raised its first checked bag fee from $25 to $30 — which amounts to about $40 when charged in U.S. currency.

The additional increase has enraged a number of customers who claim it's a "cash-grab."

Very disappointed with yet another cash grab from a Canadian airline! <a href="https://twitter.com/WestJet?ref_src=twsrc%5Etfw">@WestJet</a> now forcing customers departing from Mexico to pay USD baggage fees! What a joke. —@JPerih Hey <a href="https://twitter.com/WestJet?ref_src=twsrc%5Etfw">@WestJet</a> why did I pay $30 CAD to fly direct to Mexico. But to fly directly back to Canada I pay $30 USD per bag? Why is that? Do you always charge random countries currencies that people don’t visit? —@cannabianski

In a statement on its website in the "service fees" section, WestJet explains that its baggage fees are now based on the country a flight departs from.

That doesn't make much sense to Zielke who got hit with the $30 US fee on a return flight from Puerto Vallarta, Mexico — where the domestic currency is the much weaker Mexican peso.

"What pisses me off the most is, I never even stepped foot in the United States," she said. "Why am I paying in United States currency?"

Travelling to Mexico on Jan. 19, Zielke and her husband paid $60 for two checked bags.

On their return flight to Regina last weekend, they were charged $60 US for the same bags, which worked out to $83 — $23 more.

"What are they doing with that extra $23?" said Zielke. "I just feel like the whole thing is very sketchy."

An industry standard?

When Zielke returned home, she fired off a complaint to WestJet. The airline wrote in response that in Mexico, U.S. currency is "the popular and desired method of payment."

Zielke said she never paid in U.S. dollars when in Mexico. "I would argue it's not the preferred currency," she said.

Chris Gunderson and wife, Karen, were surprised to have to pay $60 US ($83) for two checked bags on their return WestJet flight from Mazatlan, Mexico to Kelowna, B.C. ( Submitted by Chris Gunderson)

When WestJet passenger Chris Gunderson complained about the same $30 US fee, the airline replied that it "adjusted [its] fee guidelines to meet industry standards." WestJet also gives this explanation on its website.

"I don't buy it," said Gunderson. He and his wife were floored when they had to pay $60 US ($83) for two checked bags on their return flight from Mazatlan, Mexico to Kelowna, B.C. on Dec. 21.

"It's just gouging on their part," said Gunderson.

Our guests whose flights originate out of U.S., Mexico, or Caribbean, will be charged in USD as it is their standard currency for international transactions. The reason for the change is to align with industry standard. —@WestJet

CBC News compared bag fee rules for U.S. and sun destination routes with other major Canadian airlines.

For those routes, Air Transat also charges a $30 US baggage fee for its lowest economy fare on return flights. However, passengers can avoid the U.S. charge by prepaying in Canadian funds before leaving Canada.

WestJet doesn't provide a prepayment option.

Both Sunwing and Air Canada said that for flights originating in Canada, passengers never pay a different rate for a checked bag on the return flight. Instead, they're charged the Canadian equivalent in the departing country's local currency.

Even WestJet adheres to this rule — but only for passengers flying from Europe. In those cases, the airline charges the equivalent of $30 in British pounds or Euros for a checked bag.

Vincent Pigeon and wife, Won-Hee Pigeon, got hit with a $31.50 US ($43) checked bag fee on their return flight from Phoenix to Vancouver. (Submitted by Vincent Pigeon)

"Why is flying from the Americas different?" said WestJet passenger, Vincent Pigeon.

He complained to the airline after having to pay $31.50 US ($43) to check a bag plus GST on his return flight from Phoenix to Vancouver on Jan. 18.

"That's not a fair rule," said Pigeon. "We buy the package here in Canada, the flight, everything's initiated here in Canada."

WestJet responds

WestJet told CBC News that it periodically adjusts its baggage fees based on economics.

"We believe that our fees, including the $30 USD charge departing the U.S., are competitive with the industry overall," said spokesperson, Lauren Stewart in an email.

She said that WestJet is "sorry to hear" that many passengers believe the fee is a cash-grab and points out that when flying out of the U.S., WestJet has to pay for local expenses in U.S. dollars.

Stewart said that the airline charges the $30 US bag fee for flights from other southern countries such as Mexico because WestJet only accepts four currencies: the U.S. and Canadian dollar, the British pound and the Euro. She didn't say why the airline chose to charge the bag fee in U.S. currency specifically for these countries.

While each of the passengers in this story complained to WestJet, only one of them, Gunderson, was reimbursed for the extra $23 he spent to take his two checked bags home.

The reason: he booked his flight before the US dollar bag fee took effect and never should have been charged it. He'd like to see other passengers also get their money back.

"I don't think any other WestJet customer should be charged that [fee]," said Gunderson. "They should change their policy. It's not fair."