After a month of having sent my i-131 to NSC, I faxed them a letter explaining that I needed my document expedited due to a work related trip. About 3 days later I received a letter from them saying that they would not rush my request because it wasn't a "life or death" situation.
I emailed my senator's office, (well... one of the senators in Florida), and they emailed me a form that I had to fill in and fax back to them. I also faxed the same form to NSC, and in about 10 days I received the RTD in the mail.
When I check the case status online, it still says that my application is pending.
The fax number is 402-219-6171
Hope this helps....