My J-1 waiver was approved by U.S. Department of State (DoS) in last November. The case was recommended to USCIS, and I received the recommendation too. So far, I have not received any message (even a receipt) from CIS. I called CIS, I was told I could not get any help because I have no case number from CIS. I wrote to CIS and DoS some times, but no any response. What should I do now?