Delta does it again! practically empty plane tried to switch seats to delta comfort. One row ahead of where I was sitting, mind you I paid extra for my seat location, but did not have checked bags. I asked at the gate to pay to upgrade, gladly would have paid the difference, not a money issue, Mind you if I had booked with checked bags could have gotten comfort plus seat, at littleCost. Once again Cranky rude staff "mam you cant sit here" and to 2 other girlsWho were in the same row. There section was virtually no one in the section. airline really needs to "get customer service" right and put their customer first, thats not what happens on Delta. Delta please use common sense, if you have no one sitting in comfort, imagine what a GREAT experience your customers would have if they could move where no one is sitting, it cant be about the £75-100 extra cost. Common sense would say to give your customersSomething extra if its not busy. But you have just managed to upset the few peopleWho were sitting in the section by by not accommodating your flying customers and for what? There were 4 people this happened to on the flight, who we're upset. A dad flying first class and his daughter had to fight with the rude steward. What a miserable experience. Also asked prior to check in to upgrade but were told it was not possible. I could have easily purchase the up grade or used my points. I swore I would never fly Delta again, now I really wont. This has got to be the dumbest airline. And completely a missed any opportunity to give their customer a great experience. Also, I get that the seats are extra as I always purchase upgrades, and am annoyed when people in the economy class just get free will to move up to higher class sections at no additional costs, while others have paid, But when the plane is empty in the next class section up why not give those customers a great experience, vrs the hassle. Seems common sense, and would go along way to giving customer a nicer experience