Woocommerce REST API V2: The remote server returned an error: (401) Unauthorized. Status ProtocolError

I want to update order status through Woocommerce REST Api V2 in my windows service project. I got a sample C# code to download orders from this link

Consuming WooCommerce REST API from C#

Its working fine as I am downloading orders from my local server.
But I want to update order/add order note.

I tried this

    public string UpdateOrder()
    {
        //return MakeApiCall_mine("orders/17", new Dictionary<string, string>() { { "order", "{"status":"completed"}" } });//
        return MakeApiCall_mine("orders/17");
    }
    private string MakeApiCall_mine(string endpoint, Dictionary<string, string> parameters = null, string method = "PUT")
    {
        if (parameters == null)
        {
            parameters = new Dictionary<string, string>();
        }
        parameters["oauth_consumer_key"] = this.ConsumerKey;
        parameters["oauth_timestamp"] =
            DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1, 0, 0, 0)).TotalSeconds.ToString();
        parameters["oauth_timestamp"] = parameters["oauth_timestamp"].Substring(0,
            parameters["oauth_timestamp"].IndexOf("."));
        parameters["oauth_nonce"] = Hash(parameters["oauth_timestamp"]);
        parameters["oauth_signature_method"] = "HMAC-SHA256";
        parameters["oauth_signature"] = GenerateSignature(parameters, method, endpoint);
        WebClient wc = new WebClient();
        StringBuilder sb = new StringBuilder();

        foreach (var pair in parameters)
        {
            sb.AppendFormat("&{0}={1}", HttpUtility.UrlEncode(pair.Key), HttpUtility.UrlEncode(pair.Value));
        }
        var url = this.ApiUrl + endpoint + "?" + sb.ToString().Substring(1).Replace("%5b", "%5B").Replace("%5d", "%5D");
        //var result = wc.DownloadString(url);
        wc.UploadString(url, "{"order":{"status":"completed"}}");

        //return result;
        return "";

    }

but getting error The remote server returned an error: (401) Unauthorized

My woocommerce user Permissions:Read/Write.