Ok, here we have a winner for a disastorous flight and a very poor showing by the "new" D E L T A.
First, RealDLInsider here is a Delta Executive. While he's the guy in charge of SkyMiles, perhaps he can help champion your case?
Second, I'd definitely write a letter directly to Jerry Grinstein, CEO of Delta Air Lines and copy Jim Whitehurst (I believe he's president).
Write real LETTERS to these guys, not e-mails, not faxes, not phone calls.
Be specific (as in your posting) about what happened. Also, be specific in asking what you want from Delta.
Good luck and let us know how it goes.