I went to the website of one of the senators of my state and went to help with federal agencies and then help with immigration
I filled out a form and then one of the staff will contact you…
Or you can find their number, call and leave a message saying you need help with USCIS and leave your number and email and they will contact you
This is how my senator’s office did things:
They sent you a privacy form to complete basically giving them permission to talk to USCIS on your behalf. You fill out info like receipt number and names and stuff and then you write a message with what they can do to help. You can say it has been over 15 months and the case has still not been processed or something along those lines.
Print, sign, scan, and email back. Then they will let you know when USCIS replies to them.