What to do if you did not receive EAD within 90 days

First, you can call USCIS Service Center at 1-800-375-5283. Ask for "service request" so you can get response within a week or even better, ask for interim card and get a response.

Second, you can schedule infopass appointment at local USCIS office. Personally I think this method is not really helping anything as local USCIS office no longer issue EAD. They will still forward your case to service center.

Third, after you attemp above, and get no reponse, write e mail to cisombudsman.publicaffairs@dhs.gov
with detail of your efford.

for detail stpes, check DHS webiste here.