Here is the list
(1) Contact USCIS customer services by phone and make infopass
(2) Send USCIS an expedite request
(3) Contact your congressman office
(4) Contact your Senator
(5) Contact Ombudsman office
(6) Request FOIA (Freedom of Information Act) to see the reason of delay
(7) Send a letter to the following
7.1 The secretary of the Department of Homeland Security
7.2 The US Attorney General
7.3 Your District US Attorney
7.4 The Director of USCIS
7.5 The Director of TSC or NSC
7.6 The Directo