I engaged both my congressman and one of my senators in my battle to get the Dallas district office to pick up my application and schedule an interview (they descheduled my interview because they misrouted my file, and then they let my application languish untouched for months).
In both cases, I found the representative/senator's web site. Each had a "Immigration Issue" form. I filled in the form and submitted it. In each case, about 2 weeks later I phoned up, asked for the local immigration liason and politely asked if they had received the form I had submitted. In each case, it felt like the phone call was what got things going.
In the case of my congressman (very local, he lives very close to me, and I drive by his offices each day), the liason contacted the local USCIS DO and enquired on my behalf. She reported all of the information I had found during 3 infopass appointments. She also said that there were "thousands" of people ahead of me but that the USCIS would get to my case as soon as possible.
The next day I contacted one of my senator's offices (same procedure). When the senator's liason contacted the USCIS DO, my interview was scheduled immediately (I know this, I had an InfoPass appointment the next day and found out that my interview had been scheduled). The liason sounded like an older, traditional Texas lady. I was particularly polite and chit-chatted with her as one might be expected to do here in TX. It worked. She received flowers at her office later that week (from me - I hope it helps the next person
).
To me, the key is to enlist the sympathy and the empathy of that immigration liason person. They have to talk to the USCIS on a constant basis (imagine that job -- I think I'd kill myself). You want to be the person that they feel they will expend the most effort for.
And, if it works out, make sure to make them feel like their efforts were rewarded - make it easier for the next person in line.
