I called them, but they were not much help so I talked to my school's international office. She contacted the Nebraska Service center about my case on Jan. 10th and she forwarded my expedite request to the officer handling my case. She didn't want me to fax my documents so as not to abuse the system but since nothing was happening, I faxed my supporting documents on Jan.15th. My card was ordered by the end of the day.
My cover letter stated in bold "EXPEDITE REQUEST FOR I-765 (F-1 OPT) WITH A JOB OFFER". I said that my potential boss wanted me to start immediately. Also, I said that my financial resources will continue to be depleted if I am not authorized to work ASAP. I also provided my receipt number, complete name, bday and address.
Good luck!