"VISA INTER-CHARGEABILITY", pjiang,giant_hippo,sdfsdfsdff....

Last time, I got a reviewed letter which asked the Service center to have my visa number to be INTER-CHARGEABILITY from pjiang,giant_hippo,and sdfsdfsdff. I was suggested that my attonery send this letter. I forwarded this letter to my attonery, and got his reply:

"We sent in the request for Cross Chargeability and for the return of your file from the National Visa Center...."

My questiones here are: Why did my attonery send in the request to the National Visa Center,not to the service center? What did he mean" the request for the return of your file?"