Conservative author Ann Coulter had a bone to pick with Delta Air Lines on Saturday, after she said the airline moved her from a pre-booked, "extra room" seat.

She railed against the company on Twitter, calling Delta the "worst airline in America," and complained that it had given her seat to someone who was neither old, a child, sick, nor an "air marshall (sic) or tall person." Coulter shared photos of the passenger who was given the seat she had booked, and that of a flight attendant, with her approximately 1.6 million followers.

Ann Coulter Tweet: Just when you think it's safe to fly them again, the worst airline in America is STILL: @Delta

Ann Coulter Tweet: Hey @Delta, you mind telling me why it was an "emergency" to move someone else into the seat I had carefully chosen in advance and booked?

Coulter was on a flight to West Palm Beach, Florida, from New York's LaGuardia airport when she was reassigned from an aisle to a window seat on the same exit row, with extra leg room.

Delta said Coulter had originally booked a window seat and then within 24 hours of the flight's departure, she changed it to an aisle seat on the same row. At the time of boarding, the airline said it moved Coulter to another window seat on the same row to accommodate seating requests from other passengers.

The company said there was some confusion with seating assignments during boarding, and that a flight attendant then asked the passengers to move to the seats noted on their respective tickets. Delta said its customers had complied, the flight departed without incident and crew members did not report any problems. It said it only learned of Coulter's complaints after she began tweeting about it on July 15, following the flight's arrival.

A Delta spokesman told CNBC the airline's social media and customer care teams had reached out to Coulter several times and that it had connected with her by Sunday evening. He did not elaborate on what was discussed.

On Sunday evening, Delta responded to Coulter on Twitter and said it will refund the $30 she had paid for the preferred seat. The airline also called her tweets "about our other customers and employees" unacceptable and unnecessary. Coulter also tweeted that she was still waiting for an explanation.

Delta Tweet: @AnnCoulter We're sorry you did not receive the preferred seat you paid for and will refund your $30. (cont.)

Delta Tweet: @AnnCoulter Additionally, your insults about our other customers and employees are unacceptable and unnecessary.

In a separate statement, Delta added, "Each of our employees is charged with treating each other as well as our customers with dignity and respect. And we hold each other accountable when that does not happen."

"Delta expects mutual civility throughout the entire travel experience," the statement said.

Coulter had alluded to Delta employees being rough, tweeting: ".@Delta employee questionnaire: What is your ideal job: Prison guard? Animal handler? Stasi policeman? All of the above: HIRED!" She also accused them of "summarily snatching my ticket from my hand & ordering me to move w/o explanation, compensation or apology."

Previously, when United Airlines drew criticisms for the rough-handling of a passenger and carrying him off the aircraft, Coulter was seemingly unsympathetic. She tweeted:

Tweet: Sorry about the dragging, but the convicted pill-mill doctor should be deported. Dreamland amzn.to/2p2LA6M