All I can say is to keep being persistant...I called over and over again about a RSR (route service rep, in a truck) job for almost a month. I even got to know the admin by name.
If I was going to give one bit of advice it would be that you have to get kind of lucky with timing. When I was in filling out my paperwork after I was hired, I heard the hiring manger tell his admin to disqualify all the apps in the system mostly because he just didn't have enouph time to get through them all.
Just keep on trying and you should be able to get in.