That is not entirely true. While USCIS supplied processing time actual decreased to 16 months from 16.5, actual processing is more like 12-13 months. Now regardless, congressman can put in requests that might make USCIS see if there is something specific that made your case stuck. Remember, you have 2 senators and one congressman that all of them will have form on their websites specifically for "help with federal agency" They can't force USCIS to make a decision, but they can for sure at least put in requests.
Good luck, and hope you hear something sooner rather than later!