I have tried every way possible, including email USCIS, email FBI and fax FBI, write to 3 senator and congress man. Finally, the only solution is to file a lawsuit. I found an attorney to do so. We did not really file it, just notify the FBI and USCIS that we are going to do so and sent them the mandamus to show that we are serious. It was very effective. USCIS responded within a month, which ends the long wait (almost 2 and half years).
Among all the attorneys I have asked, Daniel Huang charges less and he has been friendly over time. www.danielimmigration.com
However, be aware that there is some risk to sue for I-485 case if you think the USCIS can be picky on your case. For real family based case, there is little risk.
By filing a lawsuit, not only you are helping yourself, but also helping the other victims and helping to bring justice and a fair government policy. If a lot people start to sue, they have to find ways to solve this problem and stay on a reasonble track.