Sure, by all means, write to your representative
Paul Ryan is not my congressman. But as speaker of the House, he has a special email access site by which any American can contact him. I decided I'd had enough of his negative attitude to Donald Trump's candidacy. So I sent him an e-mail. I kept it short and to the point:
As the putative leader of the Republican Party you have an enormous influence on people in general, including those in Congress. I believe it is unbecoming of you to act in the way you are toward the Republican candidate.
I am concerned that these actions may increase the chance of Hillary Clinton being elected President. I shudder at that thought. I have children, grandchildren, and a great granddaughter; and believe Clinton's election would negatively impact them (and our country) for many years to come. Please act in a positive manner to support Mr. Trump.
I received the following response:
Thank you for contacting me with your thoughts about federal tax policy and tax reform. After more than seven years of a historically weak economic recovery, reforming the federal tax code remains among the most important domestic policy challenges facing Congress. In my role as Speaker, I am committed to making sure that the House functions in an open and transparent way to meet this challenge.
You can only guess at the disappointment I sensed with such a ridiculous, ignorant non sequitur of a response to my mail.
I've had similar meaningless responses to other posts from people in Congress. A notable example is Senator Dianne Feinstein. After several such useless attempts at correspondence, I gave up contacting her.