My RFE On June 29, 2015 submitted on 12 Sept 2015 still no status change we received receipt also and we called California customer center they said check in site only
Still status : Request for additional evidence was mailed
The only option is for your employer/attorney to follow-up w/ USCIS. If they are referring you to the site, then you can’t do anything else.
Just ensure that your RFE response package was indeed received by USCIS.