Delta put up a new website and the IT folks did a lousy job testing. On Mountain Lion with Firefox Delta won't print boarding passes and won't let you book a flight. On my Air it said I had an old browser and asked me to update. When I went to see the list of supported browsers it gave me a 404 error, page not found.
So looking for support, well they took off the Delta.com support. Funny thing, reservation people are now handling website support calls. A 50%-75% increase in call volume.
Nice job Delta.
update: After filling out a complaint form, I got a reply with a support number: 888-750-3284