It only really works if you are showing them that they are going against what they thought their base wanted. Free trade right now would probably be one where a lot of Republican members of congress would have likely been surprised to learn a year ago that there was a large percentage of their Republican voting constituency that was against free trade.

So yes, if you are a Republican with a Republican representative then calling them to voice your displeasure about Donald Trump's behavior may be beneficial. Otherwise it probably won't do much unless there really is massive numbers.