Southwest Airlines is sued for not providing refunds after meltdownNEW YORK, Jan 3 (Reuters) - Southwest Airlines (LUV.N) has been sued by a passenger who said it failed to provide refunds to passengers left stranded when an operational meltdown led the carrier to cancel more than 15,000 flights late last month.Though Southwest has promised to reimburse passengers for expenses, Capdeville said it offered only a credit to him and his daughter after scrapping their Dec. 27 flight to Portland, Oregon from New Orleans and being unable to book alternative travel.Capdeville, a Marrero, Louisiana resident, is seeking damages for passengers on Southwest flights canceled since Dec. 24, and who did not receive refunds or expense reimbursements.Southwest has said it would reimburse affected passengers for reasonable expenses such as last-minute hotel, rental car and dining costs, but it might take several weeks.In a Dec. 29 letter to Southwest Chief Executive Bob Jordan, Transportation Secretary Pete Buttigieg called the disruptions "unacceptable" and said the law requires refunds when carriers cancel flights unless passengers accept rebooking."