Contacting your representative to try to influence them is a fundamental part of democracy.
Democracy is not just voting for someone, a democratic government is intended to be directly influenced by the people continually. It's kind of the whole point of a representative democracy.
It is either part of democracy or trying to manipulate democracy, it can't factually be both for obvious reasons, I agree, contacting a representative is part of the democratic process and has been a practice happening forever.
Trying to manipulate democracy would be involving actions that aren't part of an accepted democratic process, like telling your supporters to go to assault Capitol Building and them showing up with assault rifles and pressure elected officials
Democracy is not just voting for someone, a democratic government is intended to be directly influenced by the people continually. It's kind of the whole point of a representative democracy.