[Butch Cassidy Slept Here]

Try filing this type of claim, first, with a Delta office in the UK. Then, if you do not get results, proceed to complain to European Union authorities, and/or the (UK) CAA.

You, obviously, did not arrive, as originally planned, in Manchester. Under European Union regulations, you MAY be entitled to some cash compensation. In your claim you should make clear two things: (1) The entire return trip was flown on Delta Air Lines. (2) Although you were, originally, booked to transfer in Atlanta, the fare you paid was a "through fare"--Orlando - Manchester (if this is NOT the case, then you may have no protection under E.U. regulations.).

For travel to/from Europe, I've found Lufthansa to be one of the few decent airlines. True, you must transfer in either Frankfurt, or Dusseldorf, however, as you now well know, you avoid a lot of aggravation. Lufthansa has an agreement with another bad US airline--United--to fly passengers to smaller US cities. If you book your entire trip with Lufthansa, rather than United, you have a limited degree of protection against anything United might try to do to you.