It appears that the receipt number trick alone doesn't do the job any more. If you remember, last Friday I had to call 4 times just to get through to an IO. One of those times, I gave the CSR a March 2007 PD, and she STILL refused to transfer me to an IO. She said that she can open a service inquiry and that her system says that my call doesn't warrant a transfer to an IO. They are making it more and more difficult!
Try saying that you applied for Naturalization over 2 months ago and have not received your NOA - they will automatically transfer you to an IO.