Rather than accept Frontier’s offer, Spirit said it will stick to its current plan to emerge from Chapter 11 bankruptcy.

Three U.S. senators said they want Frontier Airlines and Spirit Airlines to disclose whether they are manipulating seat fees by using customers' personal information to charge different fees to passengers on the same flight.

Budget carrier Frontier Airlines announced on Wednesday that it has made another bid for fellow discount carrier Spirit Airlines, which is in bankruptcy, for an undisclosed sum.