Well, I applied early January, received the standard acknowledgement letter around end January. Then i got the invitation for an interview, I got this second letter on February 10th (sent on the 5th, stating I had 3 working days from the 5th on to call a number in order to book a suitable date.... yeah right... I live in Switzerland... they could have given me at least an extra 2-3 days!).
Anyway, I didn't call because I got another contract in the meantime.
I suggest you give them a quick call, since they definitely are still running interviews and as High as a Kite mentioned, doing so would show your enthusiasm and might get your resume to move from the bottom to the top of the pile!!!... Good luck!
Mrs. FloatJockey