For one of these travel-industry titans, it’s time to book a one-way ticket. No refunds, no changes; just butt-kicking.

With its merger with Continental finally complete, United Airlines is now the nation’s largest carrier, which would explain why it results in the most consumer complaints. But to be named in a full one-third of all airline-related issues? Now that’s a WCIA-worthy achievement.

And it wasn’t just lost baggage or delayed flights. There were some headline-makers like the disabled military vet who says United staff kicked his dog and asked him if we was “retarded,” the passenger whose wheelchair was lost by the airline — and who received another passenger’s wheelchair as a replacement, and that dog that got sent to Ireland instead of Arizona.

Meanwhile, the airline has been accused of avoiding millions in taxes by setting up bogus offices to “receive” jet fuel, filing suit against a consumer complaint site, and reminding [STATE YOUR NAME] how much it cares about [THAT ISSUE YOU BROUGHT UP].

Then there’s Carnival, whose goofs probably don’t need to be recounted but will be anyway.

First there was the tragedy aboard the Costa Concordia, which ran aground off the coast of Italy. More than 30 people died as a result of the accident and the ship’s captain — along with Carnival management — have been accused of recklessness.

Last spring, some passengers on a Carnival ship claimed they told the captain they had spied a stranded ship floating nearby, but that no one did anything about it.

Then earlier this year came the now-infamous Poop Cruise on the Carnival Triumph. A fire on the ship left it stranded more than 100 miles from land. Then the tow rope used to haul the ship back to port snapped, causing further delays. All the while, conditions on the ship grew more and more unsanitary.

When it finally reached port, passengers were put onto buses, and driven another few hours. Of course, one of those buses had to go and break down.

Meanwhile, language in the Carnival contract makes it look like filing a lawsuit might be difficult, if not impossible, though that hasn’t stopped anyone from trying.

This was all followed by another cruise just a few weeks ago where passengers had to be flown home after a generator failure on the Dream resulted in overflowing toilets and other problems.

Please enjoy the complimentary beverage service while you vote.

VOTING FOR THIS POLL IS NOW CLOSED. CONGRATULATIONS TO CARNIVAL FOR MOVING ON TO ROUND TWO!

This is a post in our Worst Company In America 2013 series. The companies competing for this honor were chosen by you, the readers. See the entire WCIA 2013 bracket HERE.

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.