I have to agree with c100driver, HR these days exist purely to arrange the recruitment day and organise/liaise with everyone that's required to attend. I don't know the finer details of how they select who attends each recruitment, but one or two individuals scanning through probably thousands of applications doesn't make me feel very comfortable. I'd absolutely suggest a polite phone call, not an email! If you want an interview you're going to have to work for it, there are plenty of others waiting in line.