Error making POST from a json to a Web API

Question

It’s giving me an error when I try to make a POST to the API that error is:

System.Net.Webexception: Remote server returned an error: (405) Method not allowed.

The code I’m using is:

var httpWebRequest = (HttpWebRequest)WebRequest.Create("https://test-turnoverapi.lyoness.net/");


httpWebRequest.Method = "POST";
httpWebRequest.ContentType = "application/json";
httpWebRequest.Accept = "application/vnd.lyoness.servicesv1 + json";
httpWebRequest.Date = d2;
httpWebRequest.Headers.Add("Authorization", ": " + hashheader);


using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
{
    MessageBox.Show("Entrei");
    streamWriter.Write(json);
    streamWriter.Flush();
    streamWriter.Close();
}

MessageBox.Show(json);
var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
    MessageBox.Show("Entrei");
    var teste = streamReader.ReadToEnd();
    MessageBox.Show(teste);
}

I would like to know what is the problem with my code and how I can solve it.

Here is an example of a json that the Api provides :