I just wrote a very simple letter. It included my

file #, the time table of those finished steps, and my agent's name and address. Finally, asked them what's the status of the appliction, and if there was some problem, what I could did. In fact, I didn't get any response from CIC, but they sent the final approval notice in three weeks to my agent. I believe if your case is in the middle of something, they will tell you that your case is under bg check, final review or whatever; if it's close to be finished, they won't make a reply to you. Good Luck!