I’ve been a lower tier United Premium Silver flyer for years, maintaining an annual minimum 25,000 miles flown to get free checked luggage and other benefits from the airline’s loyalty program. This year, United (UAL) requires Premium Silver flyers to also spend at least $2,500 in airfares (fares excluding taxes and other fees). The higher the elite category, the higher the required revenue amount and miles flown.

As of March 1, 2015, the award miles earned on most United and United Express tickets will be based on the ticket price, instead of miles flown, rewarding those who spend the most.

Recently, I looked at my account to see how much revenue credit I’d accrued this year, and noticed that it was much lower than expected. With the next ticket purchased to fly from Los Angles to Houston, with a stopover in Dallas, I saw that the airfare quoted online was higher than the actual airfare that appeared on the e-receipt after purchase. The total cost of the ticket was the same on both, but the airfare was higher in the online quote and less on the actual e-ticket purchased.

I e-mailed United’s Web Support Desk, asking them to explain the discrepancy. If United is advertising that an airfare is $462 plus taxes and fees of $31.50 online, for a total of $493.50, why does my e-receipt say the airfare is $429.77 plus $63.73 taxes and fees, for that same total of $493.50? Does this mean I’ll only get $429 in revenue credit toward my frequent flyer status, even though I thought I’d be getting $462 in revenue credit when I bought the ticket?

Pernell Chevis at United.com Web Support Desk wrote back: “After viewing the confirmation number you provided, I show that your ticket credit is $493.50. This is the credit amount you will have if you needed to make changes to your reservation. We appreciate your e-mail and look forward to welcoming you onboard United Airlines.”

Duh. Where in my e-mail did I ask if I’d be credited the full amount toward changes in a reservation? Hoping for a more straightforward answer, I e-mailed my query again to the MileagePlus Service Center.

I got an e-mail back from Connie Johnson at the MileagePlus Service Center, saying, ”Since your question is related to the ticketing of an existing reservation for future travel, please contact United Reservations… We would be happy to help with questions regarding the MileagePlus program or your MileagePlus account. Unfortunately, we can’t assist you with other travel-related questions.”

Strike two.

I asked for a MileagePlus supervisor to look at the question, and got this response from Michael Smith at MileagePlus: “Your e-mail is specifically about booking issues. Please call Reservations at (800) 225-8900. You may ask for a supervisor on that phone call if you wish.”

So I called that number and the reservations rep said, “We don’t have anything to do with that. Let me give you Web Support.”

When I spoke with a Web Support rep, she actually had an answer. After crunching the numbers on my ticket (the example cited above), she said the airfare price included the U.S. Federal Transportation Tax online, but the tax was removed and placed with the other taxes and fees on the e-receipt.

So why isn’t that error online fixed, I asked? The current practice is deceptive advertising that makes a frequent flyer think she’ll get a higher revenue spend credit than she actually gets after buying the ticket. The Web Support rep’s response? “I’m sorry for the inconvenience.”

I asked to speak to a supervisor, and got placed on hold. After several minutes, with no one coming on the line, I hung up.

Deciding it was time for an official response, I called United’s media relations office and explained the issue. Karen May, spokesperson for the airline, confirmed what the web support rep told me. She said the U.S. excise tax is included in the airfare quote online, but is placed with the other taxes when you get your receipt, reducing the amount of the airfare itself.

And why is it done that way? “It’s been this way for some time, but we want to give our Mileage Plus customers transparency so that they’ll know what kind of revenue credit they’ll be getting,” May says. “So we are in the process of making that update, and hope to have it completed very soon.”

How long has this update been going on? “Updating our website is an ongoing process,” she notes. “We follow the Department of Transportation regulations closely, and everything is displayed as it should be. I can’t say if anyone else has complained about this, but am glad you called to ask about it.”

The good news is, there’s no discrepancy in price when you make international flight purchases online because the U.S. excise tax isn’t involved in those tickets.

So whatever airline you fly, be sure to look twice at those ticket prices. For frequent flyers, flying the friendly skies may cost you more than anticipated.