Code-share problems are not unusual, and most travelers have at least one story of an unpleasant experience when travel wasn’t quite the “seamless experience” that the airline marketing departments promise. Even the most-frequent of fliers can have their hassles.

Assuming the passengers make it to the right carrier and have ticket information in hand, these problems seem to be exacerbated with discounted tickets, infrequent fliers and smaller airline partners.

Last month, however, a Global Services (translation – “next to God”) United frequent flier found out the hard way that the United-Lufthansa partnership, one of the longest-established in the skies, isn’t perfect either. It almost cost him his trip.

It wasn’t a complicated trip – A Sunday afternoon trip San Francisco to Dusseldorf via Frankfurt. The client had a United flight to Frankfurt, over two hours of connection time in Frankfurt and a Lufthansa flight to Dusseldorf. He could have booked a straight Lufthansa connection, as Lufthansa has a flight leaving San Francisco to Frankfurt at about the same time, but for Global Services members United gives some space-available first class upgrades. And first-class for no additional charge is a powerful inducement.

Besides, not only do the two airlines partner and code-share, because this passenger was continuing on to Asia with another airline, he had a one-way, United-Lufthansa only, full-fare business class ticket too — almost $7,000.

So he checked in and everything was fine, but right before boarding an announcement was made that there would be a mechanical delay, and that United would have a “decision” in two hours.

Regular fliers have learned to dread the word “decision,” because it means they are going to decide if they can fix the plane or not. At that point, a two hour delay meant a chance to make the connection, longer meant it would not happen. And his meeting in Dusseldorf was critical with several others who were flying in just for the day.

Fortunately, Lufthansa had that nonstop flight leaving in just under an hour. In fact, the two carriers have long had these almost twin flights leaving at nearly the same time, and both of them sell seats on both flights as code-shares.

So, this should have been easy. Lufthansa told him they had seats, but only in first class. He asked United to try to organize a swap, saying he was willing to pay the difference. In short, they said no.

Now, some situations at the airport are complicated. This one wasn’t. The Lufthansa flight even also had a United flight number. The client had his ticket number, the original credit card, and there was clearly no penalty involved. (He didn’t even try to reach me because he KNEW it was a simple exchange that they should be able to do in a few minutes.)

Moreover, while this might be overly technical information, these two carriers are not just “Star Alliance partners.” United contracts for travel agency commissions, consolidator fares, corporate discounts and any other concessions have been joint contracts with Lufthansa for years. In fact, representatives of the two carriers often almost talk as if they were merged, except that they don’t want to run afoul of anti-trust legislation.

One United sales representative once said to me, “Consider us one airline.” Great, except when they aren’t.

In the end, after arguing with United for a while, my client realized Lufthansa was about to close their flight and so he ended up buying a completely new ticket for the flight. He did end up making the meeting.

On the other hand, not everyone has as much credit card float as he did. Plus, this meant that he had to max out the card he planned to use for the trip.

In addition, while we could quickly request a refund of the original ticket, airlines routinely take a month or more to credit money back, so the funds will stay tied up on his card for a while.

Could anything have been done differently?

Had the passenger lucked into someone different at United, there wouldn’t have been a problem, but so close to flight time he didn’t have a lot of options. (For passengers with more time, polite persistence often will get you to someone who can solve a problem.)

All things being equal, it’s safe to book one airline all the way through for a trip, rather than ANY code-share partners. But all things are not always equal. Had Lufthansa had the mechanical problem, the situation could have been reversed.

Perhaps the lesson, other than the fact that code-sharing and partnerships are just two more things that airlines oversell, is that incompetence and poor customer service don’t just happen to people in the back of the bus.