class Program
{
    static void Main(string[] args)
    {
        var response = new HttpClient().PostAsync("http://localhost/myservice",
            new StringContent("{ "type": "confirmation" }", Encoding.UTF8, "application/json"))
            .Result;
        Console.WriteLine(response.StatusCode);
    }
}

var client = new RestClient("http://localhost/myservice");
var request = new RestRequest("api") { Method = Method.POST };
request.AddJsonBody(new { type = "confirmation" });

var response = client.Execute(request);