Our case also went outside processing time and we did file a inquiry. I dont have the exact text of the inquiry but had written briefly about providing anything they need to process and gave a 1-2 line plea for expedited the processing of the application as it was causing personal hardship.
As a response to the inquiry we got a approval. Not sure if the inquiry resulted in the approval but its sure worth a try to put it in and hope someone looks at your file.
Best Luck ! Hope this process ends for both of us soon!
I just threw it inside "Last Action Taken on Case" text box