veggy & shovonbd
we sent the inquiry letter by certified mail a day before the approval was emailed - "after approving your case on nov 2, we ordered you a new card....." . so when we tracked the letter through usps, it was received by NSC around nov 6 or 7. and on that day (nov 7) we got another email saying "this case has been approved. on nov 7, we mailed you an approval notice..." i figured this was in response to the inquiry we mailed, or i don't know if it was SOP to send another email telling that the case was approved.
we sent the letter to PO BOX 82521, Lincoln, NE 68501-2521 (not sure of the zip). realizing that the phone inquiry system was not so helpful at all, we decided to swrite a letter because i got an FP appointment but he did not, although his application was sent earlier than mine. you might want to tell them that you are following up on the status of your application, include your name, LIN#, date of birth, receipt date and notice date. also mention that your receipt date online is different from your receipt date on the notice (if so). by the way, as per the website's instruction, don't forget to write "STATUS INQUIRY" - i wrote it just below the address on the envelope and on top of the letter like an attention line.
i hope this will help, just try. good luck to all of us!