Sooner or later you will receive a comment that you disagree with. Your initial reaction may be to question the review and defend your work. Doing so is strongly discouraged by the site.
Authors should not reply negatively or request that a reviewer change his or her rating. An opinion is subjective and is therefore always correct.
The site expects you to receive unfair and inaccurate ratings and has protections in place against them. The site excludes the highest and lowest rating on your work once it receives ten comments. You can see what reviews were excluded by looking at the individual comments for a specific work. There are also other less visible checks and balances in place. In short, ratings that are not accurate will have a negligible impact on your rating and rank.
So feel free to use the reply feature and private message system to enter a dialogue with a reviewer in a friendly manner about specific points they brought up in a comment. Or feel free to contact a reviewer if you have made changes based on that reviewers feedback. But do not use it to attack a reviewer or to be defensive about your work.