So, people in this situation might be interested in actually replying one of those messages, with the following: "I will not remove the review. Please stop contacting me. Further contact will be understood as [harassment|disturbance of peace|etc.], acc. to [insert law in your country], and passive to litigation."
Also, unless the goods in question are expensive, resist the temptation to accept a refund, in exchange for removing the review. When you're dealing with dishonest sellers, it's well worth to get a small burden (no refund) to give them a bigger one (bad rep).