Dear Anahit, here's my experience:
EU11XX
13 October 05 I-485 sent
21 October 05 NL received
2 Feb 06 FP done
30 March Infopass to inquire about interview date: we discover delay with my husband's background check
25 April INTERVIEW: we are told that my husband's file is missing and that we would receive a decision within 90 days (24 July).
Meanwhile we contacted the Senator's office, the Congresswoman's Office, the USCIS Office a number of times. NO RESULT SO FAR. We have an Infopass appointment for next Thursday 20 July.
The Senator's and Congresswoman's offices may or may not be efficient, we have no way of knowing what kind of letters they are sending out and they have a "don't contact us we'll contact you" overall attitude. Hopefully they are pushing our case.
If all else fails we are considering using a Mandamus Act, involving a COURT order.
By the way, I am the principal applicant and for all intent and purposes I am entitled to an adjudication NOW with or without my husband since there is no delay on my case. I am in the process of making that request.
Good luck to you all
Barbara