Hey Becky84,
It was driving me crazy too. I just got the call today accepting me into EY. I went to the recruitment day in MEL on the 3rd July. Do you know if your references have been checked? Mine were checked nearly three weeks ago. That should give you a guide.
If you cant take it any longer, just send them a polite email. I emailed them this morning. I got a reply a few hours later saying my file had been handed onto a specific recruitment consultant and then i got a phone call to say OK and my contract via email.
I hope you get through. Good luck.
M