回複：How to ask for help from senator or congessmen on -I-485

I have a few questions on this issue,
Which is better, senator or congressmen, or both?
-Up to you, any one is OK (Senator more powerful).

Do I need to choose the one who take care of the immigration issue, or anyone?
-All are take care of immigration issue.

Which way is better, letter or phone, fax?
-Check their website and you will find the information there.

File to the local office or DC office?
-Does not matter, but local office is more convenient.