You would be surprised at how the congresscritter's staffs look at this stuff; they are politicians for a reason, they are very susceptible to public pressure, and the best pressure comes from those who are not afraid to go the extra 1/4 mile.
I'm in NE, I have Ben Nelson(D), Chuck Hagel(R), and Fortenberry(R)...Fortenberry was sweating bullets this past cycle, in the 1st Dist, he didn't win by much, whereas here in NE it should have been a shoe in. Nelson is taking some harder stances on some items, as he promised he would when we met several times. Ben figures this will be the last shot for him before retiring in 2112.
Now Hagel is the really interesting one. I've met him only once, and we talked about vets issues 4 years ago. I never thought he was ultra RW, more moderate than weird. Looks like I was pretty close to being right on target. Hagel and I write back and forth on many issues, mostly vet and environmental issues.
His office has called me personally 13 times to get my views on mail I've sent...that is 13 times. I'm a nobody, just a Lib living in a very conservative state, but when I hear, "This is Senator Hagel's office in Washington, could you hold please, the Senator would like to speak to you", it can sure make you feel like you've had some kind of impact. I have spoken w/Senator Hagel on 3 of those 13 times, the other 10 were staff calls.
Now I'm not going to take any credit for having Hagel hop out of the GOP lockbox, but it is possible I made some impression .
The only other advice I can give you is that if you get an e-mail back or some snail mail, keep copies of both your original message and the reply, put them in a folder, and when you catch them going back on their word, cal them on it w/the message you've received; and if the congresscritter comes near your area while campaigning or just for a Town Hall Meeting GO THERE, w/those copies so you ask questions in front of those who matter, your local community...