Air Tran offered me an interview about four years ago.
I had to try for about 2 years, but what I feel got it was persistence and innovation. The most important thing you can do is be proactive. Go to HQ if you can and plunk an update with your resume down every two-four weeks. Get someone in HR to really take notice of you (in a good, professional way). Like it or not, it is scratch and claw out there. The most aggressive will prevail in the end. On the plus side, I don't think there is a lot really proactive competition in this industry, and many pilots still seem to think it's all about flight time and ratings. The world is your oyester.
Best of luck!