Besides this, another thing I want to suggest is, anytime you have any issue with USCIS, you can always contact your local congressman. You can find the name of your congressman by googling the zipcode. They will have a USCIS liason in their office, whose task is to talk to people in USCIS directly.

In my case, I forwarded such type of proof of evidence to my congressman's office, and the liason forwarded that to USCIS. The case was decided much more quicker through this route. I highly advise you to take this route.